ultrasound fetal presentation breech

Fetal Presentation, Position, and Lie (Including Breech Presentation)

• Key Points |

Abnormal fetal lie or presentation may occur due to fetal size, fetal anomalies, uterine structural abnormalities, multiple gestation, or other factors. Diagnosis is by examination or ultrasonography. Management is with physical maneuvers to reposition the fetus, operative vaginal delivery , or cesarean delivery .

Terms that describe the fetus in relation to the uterus, cervix, and maternal pelvis are

Fetal presentation: Fetal part that overlies the maternal pelvic inlet; vertex (cephalic), face, brow, breech, shoulder, funic (umbilical cord), or compound (more than one part, eg, shoulder and hand)

Fetal position: Relation of the presenting part to an anatomic axis; for transverse presentation, occiput anterior, occiput posterior, occiput transverse

Fetal lie: Relation of the fetus to the long axis of the uterus; longitudinal, oblique, or transverse

Normal fetal lie is longitudinal, normal presentation is vertex, and occiput anterior is the most common position.

Abnormal fetal lie, presentation, or position may occur with

Fetopelvic disproportion (fetus too large for the pelvic inlet)

Fetal congenital anomalies

Uterine structural abnormalities (eg, fibroids, synechiae)

Multiple gestation

Several common types of abnormal lie or presentation are discussed here.

Transverse lie

Fetal position is transverse, with the fetal long axis oblique or perpendicular rather than parallel to the maternal long axis. Transverse lie is often accompanied by shoulder presentation, which requires cesarean delivery.

Breech presentation

There are several types of breech presentation.

Frank breech: The fetal hips are flexed, and the knees extended (pike position).

Complete breech: The fetus seems to be sitting with hips and knees flexed.

Single or double footling presentation: One or both legs are completely extended and present before the buttocks.

Types of breech presentations

Breech presentation makes delivery difficult ,primarily because the presenting part is a poor dilating wedge. Having a poor dilating wedge can lead to incomplete cervical dilation, because the presenting part is narrower than the head that follows. The head, which is the part with the largest diameter, can then be trapped during delivery.

Additionally, the trapped fetal head can compress the umbilical cord if the fetal umbilicus is visible at the introitus, particularly in primiparas whose pelvic tissues have not been dilated by previous deliveries. Umbilical cord compression may cause fetal hypoxemia.

Predisposing factors for breech presentation include

Preterm labor

Uterine abnormalities

Fetal anomalies

If delivery is vaginal, breech presentation may increase risk of

Umbilical cord prolapse

Birth trauma

Perinatal death

Face or brow presentation

In face presentation, the head is hyperextended, and position is designated by the position of the chin (mentum). When the chin is posterior, the head is less likely to rotate and less likely to deliver vaginally, necessitating cesarean delivery.

Brow presentation usually converts spontaneously to vertex or face presentation.

Occiput posterior position

The most common abnormal position is occiput posterior.

The fetal neck is usually somewhat deflexed; thus, a larger diameter of the head must pass through the pelvis.

Progress may arrest in the second phase of labor. Operative vaginal delivery or cesarean delivery is often required.

Position and Presentation of the Fetus

If a fetus is in the occiput posterior position, operative vaginal delivery or cesarean delivery is often required.

In breech presentation, the presenting part is a poor dilating wedge, which can cause the head to be trapped during delivery, often compressing the umbilical cord.

For breech presentation, usually do cesarean delivery at 39 weeks or during labor, but external cephalic version is sometimes successful before labor, usually at 37 or 38 weeks.

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Variation in fetal presentation

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At the time the article was created The Radswiki had no recorded disclosures.

At the time the article was last revised Yuranga Weerakkody had no financial relationships to ineligible companies to disclose.

• Delivery presentations
• Variation in delivary presentation
• Abnormal fetal presentations

There can be many variations in the fetal presentation which is determined by which part of the fetus is projecting towards the internal cervical os . This includes:

cephalic presentation : fetal head presenting towards the internal cervical os, considered normal and occurs in the vast majority of births (~97%); this can have many variations which include

left occipito-anterior (LOA)

left occipito-posterior (LOP)

left occipito-transverse (LOT)

right occipito-anterior (ROA)

right occipito-posterior (ROP)

right occipito-transverse (ROT)

straight occipito-anterior

straight occipito-posterior

breech presentation : fetal rump presenting towards the internal cervical os, this has three main types

frank breech presentation  (50-70% of all breech presentation): hips flexed, knees extended (pike position)

complete breech presentation  (5-10%): hips flexed, knees flexed (cannonball position)

footling presentation  or incomplete (10-30%): one or both hips extended, foot presenting

other, e.g one leg flexed and one leg extended

shoulder presentation

cord presentation : umbilical cord presenting towards the internal cervical os

• 1. Fox AJ, Chapman MG. Longitudinal ultrasound assessment of fetal presentation: a review of 1010 consecutive cases. Aust N Z J Obstet Gynaecol. 2006;46 (4): 341-4. doi:10.1111/j.1479-828X.2006.00603.x - Pubmed citation
• 2. Merz E, Bahlmann F. Ultrasound in obstetrics and gynecology. Thieme Medical Publishers. (2005) ISBN:1588901475. Read it at Google Books - Find it at Amazon

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Fetal Presentation, Position, and Lie (Including Breech Presentation)

• Variations in Fetal Position and Presentation |

During pregnancy, the fetus can be positioned in many different ways inside the mother's uterus. The fetus may be head up or down or facing the mother's back or front. At first, the fetus can move around easily or shift position as the mother moves. Toward the end of the pregnancy the fetus is larger, has less room to move, and stays in one position. How the fetus is positioned has an important effect on delivery and, for certain positions, a cesarean delivery is necessary. There are medical terms that describe precisely how the fetus is positioned, and identifying the fetal position helps doctors to anticipate potential difficulties during labor and delivery.

Presentation refers to the part of the fetus’s body that leads the way out through the birth canal (called the presenting part). Usually, the head leads the way, but sometimes the buttocks (breech presentation), shoulder, or face leads the way.

Position refers to whether the fetus is facing backward (occiput anterior) or forward (occiput posterior). The occiput is a bone at the back of the baby's head. Therefore, facing backward is called occiput anterior (facing the mother’s back and facing down when the mother lies on her back). Facing forward is called occiput posterior (facing toward the mother's pubic bone and facing up when the mother lies on her back).

Lie refers to the angle of the fetus in relation to the mother and the uterus. Up-and-down (with the baby's spine parallel to mother's spine, called longitudinal) is normal, but sometimes the lie is sideways (transverse) or at an angle (oblique).

For these aspects of fetal positioning, the combination that is the most common, safest, and easiest for the mother to deliver is the following:

Head first (called vertex or cephalic presentation)

Facing backward (occiput anterior position)

Spine parallel to mother's spine (longitudinal lie)

Neck bent forward with chin tucked

Arms folded across the chest

If the fetus is in a different position, lie, or presentation, labor may be more difficult, and a normal vaginal delivery may not be possible.

Variations in fetal presentation, position, or lie may occur when

The fetus is too large for the mother's pelvis (fetopelvic disproportion).

The uterus is abnormally shaped or contains growths such as fibroids .

The fetus has a birth defect .

There is more than one fetus (multiple gestation).

Position and Presentation of the Fetus

Variations in fetal position and presentation.

Some variations in position and presentation that make delivery difficult occur frequently.

Occiput posterior position

In occiput posterior position (sometimes called sunny-side up), the fetus is head first (vertex presentation) but is facing forward (toward the mother's pubic bone—that is, facing up when the mother lies on her back). This is a very common position that is not abnormal, but it makes delivery more difficult than when the fetus is in the occiput anterior position (facing toward the mother's spine—that is facing down when the mother lies on her back).

When a fetus faces up, the neck is often straightened rather than bent,which requires more room for the head to pass through the birth canal. Delivery assisted by a vacuum device or forceps or cesarean delivery may be necessary.

Breech presentation

In breech presentation, the baby's buttocks or sometimes the feet are positioned to deliver first (before the head).

When delivered vaginally, babies that present buttocks first are more at risk of injury or even death than those that present head first.

The reason for the risks to babies in breech presentation is that the baby's hips and buttocks are not as wide as the head. Therefore, when the hips and buttocks pass through the cervix first, the passageway may not be wide enough for the head to pass through. In addition, when the head follows the buttocks, the neck may be bent slightly backwards. The neck being bent backward increases the width required for delivery as compared to when the head is angled forward with the chin tucked, which is the position that is easiest for delivery. Thus, the baby’s body may be delivered and then the head may get caught and not be able to pass through the birth canal. When the baby’s head is caught, this puts pressure on the umbilical cord in the birth canal, so that very little oxygen can reach the baby. Brain damage due to lack of oxygen is more common among breech babies than among those presenting head first.

In a first delivery, these problems may occur more frequently because a woman’s tissues have not been stretched by previous deliveries. Because of risk of injury or even death to the baby, cesarean delivery is preferred when the fetus is in breech presentation, unless the doctor is very experienced with and skilled at delivering breech babies or there is not an adequate facility or equipment to safely perform a cesarean delivery.

Breech presentation is more likely to occur in the following circumstances:

Labor starts too soon (preterm labor).

The uterus is abnormally shaped or contains abnormal growths such as fibroids .

Other presentations

In face presentation, the baby's neck arches back so that the face presents first rather than the top of the head.

In brow presentation, the neck is moderately arched so that the brow presents first.

Usually, fetuses do not stay in a face or brow presentation. These presentations often change to a vertex (top of the head) presentation before or during labor. If they do not, a cesarean delivery is usually recommended.

In transverse lie, the fetus lies horizontally across the birth canal and presents shoulder first. A cesarean delivery is done, unless the fetus is the second in a set of twins. In such a case, the fetus may be turned to be delivered through the vagina.

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INTRODUCTION

This topic will provide an overview of major issues related to breech presentation, including choosing the best route for delivery. Techniques for breech delivery, with a focus on the technique for vaginal breech delivery, are discussed separately. (See "Delivery of the singleton fetus in breech presentation" .)

TYPES OF BREECH PRESENTATION

● Frank breech – Both hips are flexed and both knees are extended so that the feet are adjacent to the head ( figure 1 ); accounts for 50 to 70 percent of breech fetuses at term.

● Complete breech – Both hips and both knees are flexed ( figure 2 ); accounts for 5 to 10 percent of breech fetuses at term.

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Definitions, incidence, risk factors, and natural history, risk factors, natural history, screening and diagnosis, physical examination, radiography, ultrasonography, referral, adjunctive imaging, and treatment, adjunctive imaging, risks of treatment, medicolegal risk to the pediatrician, best practices and state of the art, acknowledgments, lead authors, section on orthopaedics executive committee, 2014–2015, evaluation and referral for developmental dysplasia of the hip in infants.

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Brian A. Shaw , Lee S. Segal , SECTION ON ORTHOPAEDICS , Norman Y. Otsuka , Richard M. Schwend , Theodore John Ganley , Martin Joseph Herman , Joshua E. Hyman , Brian A. Shaw , Brian G. Smith; Evaluation and Referral for Developmental Dysplasia of the Hip in Infants. Pediatrics December 2016; 138 (6): e20163107. 10.1542/peds.2016-3107

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Developmental dysplasia of the hip (DDH) encompasses a wide spectrum of clinical severity, from mild developmental abnormalities to frank dislocation. Clinical hip instability occurs in 1% to 2% of full-term infants, and up to 15% have hip instability or hip immaturity detectable by imaging studies. Hip dysplasia is the most common cause of hip arthritis in women younger than 40 years and accounts for 5% to 10% of all total hip replacements in the United States. Newborn and periodic screening have been practiced for decades, because DDH is clinically silent during the first year of life, can be treated more effectively if detected early, and can have severe consequences if left untreated. However, screening programs and techniques are not uniform, and there is little evidence-based literature to support current practice, leading to controversy. Recent literature shows that many mild forms of DDH resolve without treatment, and there is a lack of agreement on ultrasonographic diagnostic criteria for DDH as a disease versus developmental variations. The American Academy of Pediatrics has not published any policy statements on DDH since its 2000 clinical practice guideline and accompanying technical report. Developments since then include a controversial US Preventive Services Task Force “inconclusive” determination regarding usefulness of DDH screening, several prospective studies supporting observation over treatment of minor ultrasonographic hip variations, and a recent evidence-based clinical practice guideline from the American Academy of Orthopaedic Surgeons on the detection and management of DDH in infants 0 to 6 months of age. The purpose of this clinical report was to provide literature-based updated direction for the clinician in screening and referral for DDH, with the primary goal of preventing and/or detecting a dislocated hip by 6 to 12 months of age in an otherwise healthy child, understanding that no screening program has eliminated late development or presentation of a dislocated hip and that the diagnosis and treatment of milder forms of hip dysplasia remain controversial.

Early diagnosis and treatment of developmental dysplasia of the hip (DDH) is important to provide the best possible clinical outcome. DDH encompasses a spectrum of physical and imaging findings, from mild instability and developmental variations to frank dislocation. DDH is asymptomatic during infancy and early childhood, and, therefore, screening of otherwise healthy infants is performed to detect this uncommon condition. Traditional methods of screening have included the newborn and periodic physical examination and selected use of radiographic imaging. The American Academy of Pediatrics (AAP) promotes screening as a primary care function. However, screening techniques and definitions of clinically important clinical findings are controversial, and despite abundant literature on the topic, quality evidence-based literature is lacking.

The AAP last published a clinical practice guideline on DDH in 2000 titled “Early Detection of Developmental Dysplasia of the Hip.” 1 The purpose of this clinical report is to provide the pediatrician with updated information for DDH screening, surveillance, and referral based on recent literature, expert opinion, policies, and position statements of the AAP and the Pediatric Orthopaedic Society of North America (POSNA), and the 2014 clinical practice guideline of the American Academy of Orthopaedic Surgeons (AAOS). 1 , – 3  

A contributing factor to the DDH screening debate is lack of a uniform definition of DDH. DDH encompasses a spectrum of pathologic hip disorders in which hips are unstable, subluxated, or dislocated and/or have malformed acetabula. 1 However, imaging advancements, primarily ultrasonography, have created uncertainty regarding whether minor degrees of anatomic and physiologic variability are clinically significant or even abnormal, particularly in the first few months of life.

Normal development of the femoral head and acetabulum is codependent; the head must be stable in the hip socket for both to form spherically and concentrically. If the head is loose in the acetabulum, or if either component is deficient, the entire hip joint is at risk for developing incongruence and lack of sphericity. Most authorities refer to looseness as instability or subluxation and the actual physical deformity of the femoral head and/or acetabulum as dysplasia, but some consider hip instability itself to be dysplasia. Further, subluxation can be static (in which the femoral head is relatively uncovered without stress) or dynamic (the hip partly comes out of the socket with stress). The Ortolani maneuver, in which a subluxated or dislocated femoral head is reduced into the acetabulum with gentle hip abduction by the examiner, is the most important clinical test for detecting newborn dysplasia. In contrast, the Barlow maneuver, in which a reduced femoral head is gently adducted until it becomes subluxated or dislocated, is a test of laxity or instability and has less clinical significance than the Ortolani maneuver. In a practical sense, both maneuvers are performed seamlessly in the clinical assessment of an infant’s hip. Mild instability and morphologic differences at birth are considered by some to be pathologic and by others to be normal developmental variants.

In summary, there is lack of universal agreement on what measurable parameters at what age constitute developmental variation versus actual disease. Despite these differences in definition, there is universal expert agreement that a hip will fare poorly if it is unstable and morphologically abnormal by 2 to 3 years of age. It is the opinion of the AAP that DDH fulfills most screening criteria outlined by Wilson and Jungner 4 and that screening efforts are worthwhile to prevent a subluxated or dislocated hip by 6 to 12 months of age.

The Ortolani maneuver, in which a subluxated or dislocated femoral head is reduced into the acetabulum with gentle hip abduction by the examiner, is the most important clinical test for detecting newborn hip dysplasia.

The incidence of developmental dislocation of the hip is approximately 1 in 1000 live births. The incidence of the entire spectrum of DDH is undoubtedly higher but not truly known because of the lack of a universal definition. Rosendahl et al 5 noted a prevalence of dysplastic but stable hips of 1.3% in the general population. A study from the United Kingdom reported a 2% prevalence of DDH in girls born in the breech position. 6  

Important risk factors for DDH include breech position, female sex, incorrect lower-extremity swaddling, and positive family history. These risk factors are thought to be additive. Other suggested findings, such as being the first born or having torticollis, foot abnormalities, or oligohydramnios, have not been proven to increase the risk of “nonsyndromic” DDH. 3 , 7  

Breech presentation may be the most important single risk factor, with DDH reported in 2% to 27% of boys and girls presenting in the breech position. 6 , 8 , 9 Frank breech presentation in a girl (sacral presentation with hips flexed and knees extended) appears to have the highest risk. 1 Most evidence supports the breech position toward the end of pregnancy rather than breech delivery that contributes to DDH. There is no clear demarcation of timing of this risk; in other words, the point during pregnancy when the DDH risk is normalized by spontaneous or external version from breech to vertex position. Mode of delivery (cesarean) may decrease the risk of DDH with breech positioning. 10 , – 12 A recent study suggested that breech-associated DDH is a milder form than DDH that is not associated with breech presentation, with more rapid spontaneous normalization. 13  

Genetics may contribute more to the risk of DDH than previously considered “packaging effects.” If a monozygotic twin has DDH, the risk to the other twin is approximately 40%, and the risk to a dizygotic twin is 3%. 14 , 15 Recent research has confirmed that the familial relative risk of DDH is high, with first-degree relatives having 12 times the risk of DDH over controls. 16 , – 18 The left hip is more likely to be dysplastic than the right, which may be because of the more common in utero left occiput anterior position in nonbreech infants. 1 The AAOS clinical practice guideline considers breech presentation and family history to be the 2 most important risk factors in DDH screening. 3  

A lesser-known but important risk factor is the practice of swaddling, which has been gaining popularity in recent years for its noted benefits of enhancing better sleep patterns and duration and minimizing hypothermia. However, these benefits are countered by the apparent increased rates of DDH observed in several ethnic groups, such as Navajo Indian and Japanese populations, that have practiced traditional swaddling techniques. Traditional swaddling maintains the hips in an extended and adducted position, which increases the risk of DDH. However, the concept of “safe swaddling,” which allows for hip flexion and abduction and knee flexion, has been shown to lessen the risk of DDH ( http://hipdysplasia.org/developmental-dysplasia-of-the-hip/hip-healthy-swaddling/ ). Parents can be taught the principles of safe infant sleep, including supine position in the infant’s own crib and not the parent’s bed, with no pillows, bumpers, or loose blankets. 19 , – 24 The POSNA, International Hip Dysplasia Institute, AAOS, United States Bone and Joint Initiative, and Shriners Hospitals for Children have published a joint statement regarding the importance of safe swaddling in preventing DDH. 25  

In general, risk factors are poor predictors of DDH. Female sex, alone without other known risk factors, accounts for 75% of DDH. This emphasizes the importance of a careful physical examination of all infants in detecting DDH. 6 A recent survey showed poor consensus on risk factors for DDH from a group of experts. 26  

In general, risk factors are poor predictors of DDH. Female sex, alone without other known risk factors, accounts for 75% of DDH.

Clinical and imaging studies show that the natural history of mild dysplasia and instability noted in the first few weeks of life is typically benign. Barlow-positive (subluxatable and dislocatable) hips resolve spontaneously, and Barlow himself noted that the mild dysplasia in all 250 newborn infants with positive test results in his original study resolved spontaneously. 27 , – 32  

Conversely, the natural history of a child with hip dysplasia at the more severe end of the disease spectrum (subluxation or dislocation) by walking age is less satisfactory than children treated successfully at a younger age. Without treatment, these children will likely develop a limp, limb length discrepancy, and limited hip abduction. This may result in premature degenerative arthritis in the hip, knee, and low back. The burden of disability is high, because most affected people become symptomatic in their teens and early adult years, and most require complex hip salvage procedures and/or replacement at an early age.

The 2000 AAP clinical practice guideline recommended that all newborn infants be screened for DDH by physical examination, with follow-up at scheduled well-infant periodic examinations. The POSNA, the Canadian Task Force on DDH, and the AAOS have also advocated newborn and periodic screening. A 2006 report by the US Preventive Services Task Force (USPSTF) resulted in controversy regarding DDH screening. By using a data-driven model and a strong emphasis on the concept on predictors of poor health, the USPSTF report gave an “I” recommendation, meaning that the evidence was insufficient to recommend routine screening for DDH in infants as a means to prevent adverse outcomes. 1 , – 3 , 33 , – 35 However, on the basis of the body of evidence when evaluated from the perspective of a clinical practice model, the AAP advocates for DDH screening.

In its report, the USPSTF noted that avascular necrosis (AVN) is the most common (up to 60%) and severe potential harm of both surgical and nonsurgical interventions. 33 Williams et al 36 reported the risk of AVN to be less than 1% with screening, early detection, and the use of the Pavlik harness. In a long-term follow-up study of a randomized controlled trial from Norway, the authors reported no cases of AVN and no increased risk of harm with increased treatment. 37 The USPSTF also raised concerns about the psychological consequences or stresses with early diagnosis and intervention. Gardner et al 38 found that the use of hip ultrasonography allowed for reduction of treatment rates without adverse clinical or psychological outcomes. Thus, the concerns of AVN and psychological distress or potential predictors of poor health have not been supported in literature not referenced in the USPSTF report.

In 2 well-designed, randomized controlled trial studies from Norway, the prevalence of late DDH presentation was reduced from 2.6 to 3.0 per 1000 to 0.7 to 1.3 per 1000 by using either selective or universal hip ultrasonographic screening. Neither study reached statistical significance because of the inadequate sample size on the basis of prestudy rates of late-presentation DDH. Despite this, both centers have introduced selective hip ultrasonography as part of their routine newborn screening. 39 , 40 Clarke et al 32 also demonstrated a decrease in late DDH presentation from 1.28 per 1000 to 0.74 per 1000 by using selective hip ultrasonography in a prospective cohort of patients over a 20-year period.

The term “surveillance” may be useful nomenclature to consider in place of screening, because, by definition, it means the close monitoring of someone or something to prevent an adverse outcome. The term surveillance reinforces the concept of periodic physical examinations as part of well-child care visits until 6 to 9 months of age and the use of selective hip ultrasonography as an adjunct imaging tool or an anteroposterior radiograph of the pelvis after 4 months of age for infants with identified risk factors. 3 , 5 , 32 , 41  

Wilson and Jungner 4 outlined 10 principles or criteria to consider when determining the utility of screening for a disease. The AAP believes DDH fulfills most of these screening criteria ( Table 1 ), except for an understanding of the natural history of hip dysplasia and an agreed-on policy of whom to treat. The 2006 USPSTF report and the AAOS clinical practice guideline provide a platform to drive future research in these 2 areas. Screening for DDH is important, because the condition is initially occult, easier to treat when identified early, and more likely to cause long-term disability if detected late. A reasonable goal for screening is to prevent the late presentation of DDH after 6 months of age.

World Health Organization Criteria for Screening for Health Problems

The physical examination is by far the most important component of a DDH screening program, with imaging by radiography and/or ultrasonography playing a secondary role. It remains the “cornerstone” of screening and/or surveillance for DDH, and the available evidence supports that primary care physicians serially examine infants previously screened with normal hip examinations on subsequent visits up to 6 to 9 months of age. 3 , 41 , – 44 Once a child is walking, a dislocated hip may manifest as an abnormal gait.

The 2000 AAP clinical practice guideline gave a detailed description of the examination, including observing for limb length discrepancy, asymmetric thigh or gluteal folds, and limited or asymmetric abduction, as well as performing Barlow and Ortolani tests. 1 It is essential to perform these manual tests gently. By ∼3 months of age, a dislocated hip becomes fixed, limiting the usefulness and sensitivity of the Barlow and Ortolani tests. By this age, restricted, asymmetric hip abduction of the involved hip becomes the most important finding (see video available at http://www.aap.org/sections/ortho ). Diagnosing bilateral DDH in the older infant can be difficult because of symmetry of limited abduction.

Although ingrained in the literature, the significance and safety of the Barlow test is questioned. Barlow stated in his original description that the test is for laxity of the hip joint rather than for an existing dislocation. The Barlow test has no proven predictive value for future hip dislocation. If performed frequently or forcefully, it is possible that the maneuver itself could create instability. 45 , 46 The AAP recommends, if the Barlow test is performed, that it be done by gently adducting the hip while palpating for the head falling out the back of the acetabulum and that no posterior-directed force be applied. One can think of the Barlow and Ortolani tests as a continuous smooth gentle maneuver starting with the hip flexed and adducted, with gentle anterior pressure on the trochanter while the hip is abducted to feel whether the hip is locating into the socket, followed by gently adducting the hip and relieving the anterior pressure on the trochanter while sensing whether the hip slips out the back. The examiner should not attempt to forcefully dislocate the femoral head (see video available at http://www.aap.org/sections/ortho ).

“Hip clicks” without the sensation of instability are clinically insignificant. 47 Whereas the Ortolani sign represents the palpable sensation of the femoral head moving into the acetabulum over the hypertrophied rim of the acetabular cartilage (termed neolimbus), isolated high-pitched clicks represent the movement of myofascial tissues over the trochanter, knee, or other bony prominences and are not a sign of hip dysplasia or instability.

Plain radiography becomes most useful by 4 to 6 months of age, when the femoral head secondary center of ossification forms. 48 Limited evidence supports obtaining a properly positioned anteroposterior radiograph of the pelvis. 3 If the pelvis is rotated or if a gonadal shield obscures the hip joint, then the radiograph should be repeated. Hip asymmetry, subluxation, and dislocation can be detected on radiographs when dysplasia is present. There is debate about whether early minor radiographic variability (such as increased acetabular index) constitutes actual disease. 31 Radiography is traditionally indicated for diagnosis of the infant with risk factors or an abnormal examination after 4 months of age. 1 , 2 , 8 , 49  

Ultrasonography can provide detailed static and dynamic imaging of the hip before femoral head ossification. The American Institute of Ultrasound in Medicine and the American College of Radiology published a joint guideline for the standardized performance of the infantile hip ultrasonographic examination. 50 Static ultrasonography shows coverage of the femoral head by the cartilaginous acetabulum (α angle) at rest, and dynamic ultrasonography demonstrates a real-time image of the Barlow and Ortolani tests.

Ultrasonographic imaging can be universal for all infants or selective for those at risk for having DDH. Universal newborn ultrasonographic screening is not recommended in North America because of the expense, inconvenience, inconsistency, subjectivity, and high false-positive rates, given an overall population disease prevalence of 1% to 2%. 3 Rather, selective ultrasonographic screening is recommended either to clarify suspicious findings on physical examination after 3 to 4 weeks of age or to detect clinically silent DDH in the high-risk infant from 6 weeks to 4 to 6 months of age. 1 , 2 , 35 , 50 Two prospective randomized clinical trials from Norway support selective ultrasonographic imaging when used in conjunction with high-quality clinical screening. 39 , 40  

Roposch and colleagues 51 , 52 contend that experts cannot reach a consensus on what is normal, abnormal, developmental variation, or simply uncertain regarding much ultrasonographic imaging, thereby confounding referral and treatment recommendations. Several studies have demonstrated that mild ultrasonographic abnormalities usually resolve spontaneously, fueling the controversy over what imaging findings constitute actual disease requiring treatment. 5 , 30 , 51 , 53 , – 56  

The concept of surveillance for DDH emphasizes the importance of repeated physical examinations and the adjunct use of selective hip ultrasonography after 6 weeks of age or an anteroposterior radiograph of the pelvis after 4 months of age for infants with questionable or abnormal findings on physical examination or with identified risk factors. Ultrasonography is not necessary for a frankly dislocated hip (Ortolani positive) but may be desired by the treating physician. Physiologic joint capsular laxity and immature acetabular development before 6 weeks of age may limit the accuracy of hip ultrasonography interpretations. 39 , 40 There is no consensus on exact timing of and indications for ultrasonography among expert groups. 26 , 57 However, ultrasonographic imaging does have a management role in infants younger than 6 weeks undergoing abduction brace treatment of unstable hips identified on physical examination. 3  

Early detection and referral of infants with DDH allows appropriate intervention with bracing or casting, which may prevent the need for reconstructive surgery. Primary indications for referral include an unstable (positive Ortolani test result) or dislocated hip on clinical examination. Because most infants with a positive Barlow test result at either the newborn or 2-week examination stabilize on their own, these infants should have sequential follow-up examinations as part of the concept of surveillance. This recommendation differs from the 2000 AAP clinical practice guideline. 1 Any child with limited hip abduction or asymmetric hip abduction after the neonatal period (4 weeks) should be referred. Relative indications for referral include infants with risk factors for DDH, a questionable examination, and pediatrician or parental concern. 1  

Recommendations for the evaluation and management of infants with risk factors for DDH but with normal findings on physical examination continue to evolve. The 2000 AAP clinical practice guideline recommended hip ultrasonography at 6 weeks of age or radiography of the pelvis and hips at 4 months of age in girls with a positive family history of DDH or breech presentation. The AAP clinical practice guideline also stated that hip ultrasonographic examinations remain an option for all infants born breech. 1 The recent AAOS report found that moderate evidence supports an imaging study before 6 months of age in infants with breech presentation, family history, and/or history of clinical instability. 3 , 58 , – 60  

Consider imaging before 6 months of age for male or female infants with normal findings on physical examination and the following risk factors:

Breech presentation in third trimester (regardless of cesarean or vaginal delivery)

Positive family history

History of previous clinical instability

Parental concern

History of improper swaddling

Suspicious or inconclusive physical examination

Refinement in the term “breech presentation” as a risk factor for DDH is needed to determine whether selective hip ultrasonography at 6 weeks or radiography before 6 months of age is needed for an infant with a normal clinical hip examination. More specific variables, such as mode of delivery, type of breech position, or breech position at any time during the pregnancy or in the third trimester, have received little attention to date. The AAOS clinical practice guideline reported 6 studies addressing breech presentation, but all were considered low-strength evidence. 3 Thus, the literature is not adequate enough to allow specific guidance. The risk is thought to be greater for frank breech (hips flexed, knees extended) in the last trimester. 1  

Lacking expert consensus of risk factors for DDH, 26 the questions of whether to obtain additional imaging studies with a normal clinical hip examination is ultimately best left to one’s professional judgment. One must consider, however, that the overall probability of a clinically stable hip to later dislocate is very low.

Because of the variability in performance and interpretation of the hip ultrasonographic examination and varying thresholds for treatment, the requesting physician might consider developing a regional protocol in conjunction with a consulting pediatric orthopedist and pediatric radiologist. Specific criteria for imaging and referral based on local resources can promote consistency in evaluation and treatment of suspected DDH. Realistically, many families may not have ready access to quality infant hip ultrasonography, and this may determine the choice of obtaining a pelvic radiograph instead of an ultrasound. 61  

Recommendations for treatment are based on the clinical hip examination and the presence or absence of imaging abnormalities. Infants with a stable clinical hip examination but with abnormalities noted on ultrasonography can be observed without a brace. 3 , 56  

The initiation of abduction brace treatment, either immediate or delayed, for clinically unstable hips is supported by several studies. 3 , 62 , – 64 In a randomized clinical trial, Gardiner and Dunn 62 found no difference in hip ultrasonography findings or clinical outcome for infants with dislocatable hips treated with either immediate or delayed abduction bracing at 6- and 12-month follow-up. The infants in the delayed group (2 weeks) were treated with abduction bracing if hip instability persisted or the hip ultrasonographic abnormalities did not improve. 62  

Treatment of clinically unstable hips usually consists of bracing when discovered in early infancy and closed reduction with adductor tenotomy and spica cast immobilization when noted later. After 18 months of age, open surgery is generally recommended.

As previously noted, the 2006 USPSTF report noted a high rate of AVN, up to 60% with both surgical and nonsurgical intervention. 33 Other studies have reported much lower rates of AVN. 36 , 37 One prospective study reported a zero prevalence of AVN by 6 years of age in mildly dysplastic hips treated with bracing. 30  

However, abduction brace treatment is not innocuous. The potential risks include AVN, temporary femoral nerve palsy, and obturator (inferior) hip dislocation. 65 , – 67 One study demonstrated a 7% to 14% risk of complications after treatment in a Pavlik harness. The risk was greater in hips that did not reduce in the brace. 33 Precautions such as avoiding forced abduction in the harness, stopping treatment after 3 weeks if the hip does not reduce, and proper strap placement with weekly monitoring is important to minimize the risks associated with brace treatment. 68 , 69 Double diapering is a probably harmless but ineffective treatment of true DDH.

What remains controversial is whether the selective use of ultrasonography reduces or increases treatment. A randomized controlled study from the United Kingdom showed that approximately half of all positive physical examination findings were falsely positive (ie, normal ultrasonography results) and that the use of ultrasonography in clinically suspect hips actually reduced DDH treatment. 60 However, in the United States and Canada, 21 the reverse appears to be true. In the current medicolegal climate that encourages a defensive approach, liberal use of ultrasonography in the United States and Canada has clearly fostered overdiagnosis and overtreatment of DDH, despite best-available literature supporting observation of mild dysplasia. 33 , – 35 , 70  

Undetected or late-developing DDH is a liability concern for the pediatrician, generating anxiety and a desire for guidance in best screening methodology. 71 Unfortunately, this fear may also provoke overdiagnosis and overtreatment. “Late-presenting” DDH is a more accurate term than “missed” to use when DDH is first diagnosed in a walking-aged child who had appropriate clinical examinations during infancy. 72 , 73  

Although there is no universally recognized DDH screening standard, the AAP endorses the concept of surveillance or periodic physical examinations until walking age, with selective use of either hip ultrasonography or radiography, depending on age. The AAP cautions against overreliance on ultrasonography as a diagnostic test and encourages its use as an adjunctive secondary screen and an aid to treatment of established DDH. Notably, no screening program has been shown to completely eliminate the risk of a late-presenting dislocated hip. 69  

The electronic health record can be used to provide a template, reminder, and documentation tool for the periodic examination. It also can be useful in the transition and comanagement of children with suspected DDH by providing effective information transfer between consultants and primary care physicians and ensuring follow-up. Accurate documented communication between providers is important to provide continuity of care for this condition, and it is also important to explain to the parent(s) and document those instances when observation is used as a planned strategy so it is less likely to be misinterpreted as negligence.

The AAP, POSNA, AAOS, and Canadian DDH Task Force recommend newborn and periodic surveillance physical examinations for DDH to include detection of limb length discrepancy, examination for asymmetric thigh or buttock (gluteal) creases, performing the Ortolani test for stability (performed gently and which is usually negative after 3 months of age), and observing for limited abduction (generally positive after 3 months of age). Use of electronic health records can be considered to prompt and record the results of periodic hip examinations. The AAP recommends against universal ultrasonographic screening.

Selective hip ultrasonography can be considered between the ages of 6 weeks and 6 months for “high-risk” infants without positive physical findings. High risk is a relative and controversial term, but considerations include male or female breech presentation, a positive family history, parental concern, suspicious but inconclusive periodic examination, history of a previous positive instability physical examination, and history of tight lower-extremity swaddling. Because most DDH occurs in children without risk factors, physical examination remains the primary screening tool.

It is important that infantile hip ultrasonography be performed and interpreted per American Institute of Ultrasound in Medicine and the American College of Radiology guidelines by experienced, trained examiners. Developing local criteria for screening imaging and referral based on best resources may promote more uniform and cost-effective treatment. Regional variability of ultrasonographic imaging quality can lead to under- or overtreatment.

Most minor hip anomalies observed on ultrasonography at 6 weeks to 4 months of age will resolve spontaneously. These include minor variations in α and β angles and subluxation (“uncoverage”) with stress maneuvers. Current levels of evidence do not support recommendations for treatment versus observation in any specific case of minor ultrasonographic variation. Care is, therefore, individualized through a process of shared decision-making in this setting of inadequate information.

Radiography (anteroposterior and frog pelvis views) can be considered after 4 months of age for the high-risk infant without physical findings or any child with positive clinical findings. Age 4 to 6 months is a watershed during which either imaging modality may be used; radiography is more readily available, has a lower rate of false-positive results, and is less expensive than ultrasonography but involves a very low dose of radiation.

A referral to an orthopedist for DDH does not require ultrasonography or radiography. The primary indication for referral includes an unstable (positive Ortolani test result) or dislocated hip on clinical examination. Any child with limited hip abduction or asymmetric hip abduction after the neonatal period (4 weeks of age) should be referred for evaluation. Relative indications for referral include infants with risk factors for DDH, a questionable examination, and pediatrician or parental concern.

Evidence strongly supports screening for and treatment of hip dislocation (positive Ortolani test result) and initially observing milder early forms of dysplasia and instability (positive Barlow test result). Depending on local custom, either the pediatrician or the orthopedist can observe mild forms by periodic examination and possible follow-up imaging, but actual treatment should be performed by an orthopedist.

A reasonable goal for the primary care physician should be to diagnose hip subluxation or dislocation by 6 months of age by using the periodic physical examination. Selective ultrasonography or radiography may be used in consultation with a pediatric radiologist and/or orthopedist. No screening program has been shown to completely eliminate the risk of a late presentation of DDH. There is no high-level evidence that milder forms of dysplasia can be prevented by screening and early treatment.

Tight swaddling of the lower extremities with the hips adducted and extended should be avoided. The concept of “safe” swaddling, which does not restrict hip motion, minimizes the risk of DDH.

Treatment of neonatal DDH is not an emergency, and in-hospital initiation of bracing is not required. Orthopaedic consultation can be safely obtained within several weeks of discharge for an infant with a positive Ortolani test result. Infants with a positive Barlow test results should be reexamined and referred to an orthopedist if they continue to show clinical instability.

American Academy of Orthopaedic Surgeons

American Academy of Pediatrics

avascular necrosis

developmental dysplasia of the hip

Pediatric Orthopaedic Society of North America

US Preventive Services Task Force

This document is copyrighted and is property of the American Academy of Pediatrics and its Board of Directors. All authors have filed conflict of interest statements with the American Academy of Pediatrics. Any conflicts have been resolved through a process approved by the Board of Directors. The American Academy of Pediatrics has neither solicited nor accepted any commercial involvement in the development of the content of this publication.

Clinical reports from the American Academy of Pediatrics benefit from expertise and resources of liaisons and internal (AAP) and external reviewers. However, clinical reports from the American Academy of Pediatrics may not reflect the views of the liaisons or the organizations or government agencies that they represent.

The guidance in this report does not indicate an exclusive course of treatment or serve as a standard of medical care. Variations, taking into account individual circumstances, may be appropriate.

All clinical reports from the American Academy of Pediatrics automatically expire 5 years after publication unless reaffirmed, revised, or retired at or before that time.

The authors thank Charles Price, MD, FAAP, Ellen Raney, MD, FAAP, Joshua Abzug, MD, FAAP, and William Hennrikus, MD, FAAP, for their valuable contributions to this report.

Brian A. Shaw, MD, FAAOS, FAAP

Lee S. Segal, MD, FAAP

Norman Y. Otsuka, MD, FAAP, Chairperson

Richard M. Schwend, MD, FAAP, Immediate Past Chairperson

Theodore John Ganley, MD, FAAP

Martin Joseph Herman, MD, FAAP

Joshua E. Hyman, MD, FAAP

Brian G. Smith, MD, FAAP

Niccole Alexander, MPP

Competing Interests

Re: breech presentation in preterm infants.

Thanks for the excellent review highlighting the controversies around screening, imaging and management of DDH. I have a question to the authors re: preterm infants. If an infant is born premature in third trimester with breech presentation and a normal hip examination at birth, would the authors recommend considering a hip ultrasound after 6 weeks post-menstrual age or 6 weeks chronologic age?

RE: Late diagnosis of developmental dysplasia of the hip can be eradicated

The survey published by Shaw and al in the December issue of Pediatrics concluded that no screening program has eliminated late development or presentation of a dislocated hip (1).

In the literature, there is controversy over widespread ultrasound screening since its ability to prevent late DDH diagnosis has not been proven (2,3). Techniques mainly relied on acetabular morphology classifications with no clear cut-off for early DDH diagnosis. Results are not enough reproducible for a large screening program involving non-expert radiologists (4). Moreover the effect of hip instability on acetabular shape may not be seen at one month old. These three reasons explain the failure of almost all screening programs based on these techniques.

Our experience is based on dynamic assessment of the femoral head position based on pubo-femoral distance (PFD) measurements. The normal PFD is lower than or equal to 6mm, with no more than 1.5mm between the hips (5). This simple, reliable, and reproducible method was easily taught to general radiologists involved in the screening program. With the support of perinatal network pediatricians, ultrasound screening was offered to all girls and to boys presenting with risk factors or abnormalities on clinical examination at one month old. All reports indicate a prevalence of 90% for girls, 70% with no risk factors. All infants with positive screenings were immediately referred to multidisciplinary teams involving an expert radiologist and orthopedic pediatrician. At one month old, reducible hip instability was always successfully treated by abduction splint. In 2013, we published that late diagnosis of DDH was eradicated from our region (annual births: 14,000) over a 3-year period from 2009 to 2011 (5). This period has now reached 8 years in a region of more than 1 million inhabitants in which our institution is the only referral center. Brittany (France), country of Dr Le Damany who described this disease, has a high prevalence of DDH (6/1000).

These long-term results are unique and confirm that ultrasound measurement of PFD provides a clear cut-off for DDH detection. Based on this simple technique, widespread screening, at least in girls, could eradicate late DDH diagnosis.

References:

1. Shaw BA, Segal LS. Evaluation and Referral for Developmental Dysplasia of the Hip in Infants. Pediatrics. 2016;138(6):e20163107 2. von Kries R, Ihme N, Altenhofen L, Niethard FU, Krauspe R, Rückinger S. General ultrasound screening reduces the rate of first operative procedures for developmental dysplasia of the hip: a case-control study. J Pediatr. 2012;160(2):271–5. 3. Laborie LB, Markestad TJ, Davidsen H, Brurås KR, Aukland SM, Bjørlykke JA, et al. Selective ultrasound screening for developmental hip dysplasia: effect on management and late detected cases. A prospective survey during 1991-2006. Pediatr Radiol. 2014;44(4):410–24.

4. Roposch A, Moreau NM, Uleryk E, Doria AS (2006) Developmental dysplasia of the hip: quality of reporting of diagnostic accuracy for US. Radiology, 241(3):854-860.. 5. Tréguier C, Chapuis M, Branger B, Bruneau B, Grellier A, Chouklati K, et al. Pubo-femoral distance: an easy sonographic screening test to avoid late diagnosis of developmental dysplasia of the hip. Eur Radiol. 2013 Mar;23(3):836–44.

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Breech Births

In the last weeks of pregnancy, a baby usually moves so his or her head is positioned to come out of the vagina first during birth. This is called a vertex presentation. A breech presentation occurs when the baby’s buttocks, feet, or both are positioned to come out first during birth. This happens in 3–4% of full-term births.

What are the different types of breech birth presentations?

• Complete breech: Here, the buttocks are pointing downward with the legs folded at the knees and feet near the buttocks.
• Frank breech: In this position, the baby’s buttocks are aimed at the birth canal with its legs sticking straight up in front of his or her body and the feet near the head.
• Footling breech: In this position, one or both of the baby’s feet point downward and will deliver before the rest of the body.

What causes a breech presentation?

The causes of breech presentations are not fully understood. However, the data show that breech birth is more common when:

• You have been pregnant before
• In pregnancies of multiples
• When there is a history of premature delivery
• When the uterus has too much or too little amniotic fluid
• When there is an abnormally shaped uterus or a uterus with abnormal growths, such as fibroids
• The placenta covers all or part of the opening of the uterus placenta previa

How is a breech presentation diagnosed?

A few weeks prior to the due date, the health care provider will place her hands on the mother’s lower abdomen to locate the baby’s head, back, and buttocks. If it appears that the baby might be in a breech position, they can use ultrasound or pelvic exam to confirm the position. Special x-rays can also be used to determine the baby’s position and the size of the pelvis to determine if a vaginal delivery of a breech baby can be safely attempted.

Can a breech presentation mean something is wrong?

Even though most breech babies are born healthy, there is a slightly elevated risk for certain problems. Birth defects are slightly more common in breech babies and the defect might be the reason that the baby failed to move into the right position prior to delivery.

Can a breech presentation be changed?

It is preferable to try to turn a breech baby between the 32nd and 37th weeks of pregnancy . The methods of turning a baby will vary and the success rate for each method can also vary. It is best to discuss the options with the health care provider to see which method she recommends.

Medical Techniques

External Cephalic Version (EVC)  is a non-surgical technique to move the baby in the uterus. In this procedure, a medication is given to help relax the uterus. There might also be the use of an ultrasound to determine the position of the baby, the location of the placenta and the amount of amniotic fluid in the uterus.

Gentle pushing on the lower abdomen can turn the baby into the head-down position. Throughout the external version the baby’s heartbeat will be closely monitored so that if a problem develops, the health care provider will immediately stop the procedure. ECV usually is done near a delivery room so if a problem occurs, a cesarean delivery can be performed quickly. The external version has a high success rate and can be considered if you have had a previous cesarean delivery.

ECV will not be tried if:

• You are carrying more than one fetus
• There are concerns about the health of the fetus
• You have certain abnormalities of the reproductive system
• The placenta is in the wrong place
• The placenta has come away from the wall of the uterus ( placental abruption )

Complications of EVC include:

• Prelabor rupture of membranes
• Changes in the fetus’s heart rate
• Placental abruption
• Preterm labor

Vaginal delivery versus cesarean for breech birth?

Most health care providers do not believe in attempting a vaginal delivery for a breech position. However, some will delay making a final decision until the woman is in labor. The following conditions are considered necessary in order to attempt a vaginal birth:

• The baby is full-term and in the frank breech presentation
• The baby does not show signs of distress while its heart rate is closely monitored.
• The process of labor is smooth and steady with the cervix widening as the baby descends.
• The health care provider estimates that the baby is not too big or the mother’s pelvis too narrow for the baby to pass safely through the birth canal.
• Anesthesia is available and a cesarean delivery possible on short notice

What are the risks and complications of a vaginal delivery?

In a breech birth, the baby’s head is the last part of its body to emerge making it more difficult to ease it through the birth canal. Sometimes forceps are used to guide the baby’s head out of the birth canal. Another potential problem is cord prolapse . In this situation the umbilical cord is squeezed as the baby moves toward the birth canal, thus slowing the baby’s supply of oxygen and blood. In a vaginal breech delivery, electronic fetal monitoring will be used to monitor the baby’s heartbeat throughout the course of labor. Cesarean delivery may be an option if signs develop that the baby may be in distress.

When is a cesarean delivery used with a breech presentation?

Most health care providers recommend a cesarean delivery for all babies in a breech position, especially babies that are premature. Since premature babies are small and more fragile, and because the head of a premature baby is relatively larger in proportion to its body, the baby is unlikely to stretch the cervix as much as a full-term baby. This means that there might be less room for the head to emerge.

Want to Know More?

• Creating Your Birth Plan
• Labor & Birth Terms to Know
• Cesarean Birth After Care

Compiled using information from the following sources:

• ACOG: If Your Baby is Breech
• William’s Obstetrics Twenty-Second Ed. Cunningham, F. Gary, et al, Ch. 24.
• Danforth’s Obstetrics and Gynecology Ninth Ed. Scott, James R., et al, Ch. 21.

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Head down, face up

When a baby is head down, face up, the medical term for it is the cephalic occiput posterior position. In this position, it might be harder for a baby's head to go under the pubic bone during delivery. That can make labor take longer.

Most babies who begin labor in this position eventually turn to be face down. If that doesn't happen, and the second stage of labor is taking a long time, a member of the health care team may reach through the vagina to help the baby turn. This is called manual rotation.

In some cases, a baby can be born in the head-down, face-up position. Use of forceps or a vacuum device to help with delivery is more common when a baby is in this position than in the head-down, face-down position. In some cases, a C-section delivery may be needed.

Frank breech

When a baby's feet or buttocks are in place to come out first during birth, it's called a breech presentation. This happens in about 3% to 4% of babies close to the time of birth. The baby shown below is in a frank breech presentation. That's when the knees aren't bent, and the feet are close to the baby's head. This is the most common type of breech presentation.

If you are more than 36 weeks into your pregnancy and your baby is in a frank breech presentation, your health care professional may try to move the baby into a head-down position. This is done using a procedure called external cephalic version. It involves one or two members of the health care team putting pressure on your belly with their hands to get the baby to roll into a head-down position.

If the procedure isn't successful, or if the baby moves back into a breech position, talk with a member of your health care team about the choices you have for delivery. Most babies in a frank breech position are born by planned C-section.

Complete and incomplete breech

A complete breech presentation, as shown below, is when the baby has both knees bent and both legs pulled close to the body. In an incomplete breech, one or both of the legs are not pulled close to the body, and one or both of the feet or knees are below the baby's buttocks. If a baby is in either of these positions, you might feel kicking in the lower part of your belly.

If you are more than 36 weeks into your pregnancy and your baby is in a complete or incomplete breech presentation, your health care professional may try to move the baby into a head-down position. This is done using a procedure called external cephalic version. It involves one or two members of the health care team putting pressure on your belly with their hands to get the baby to roll into a head-down position.

If the procedure isn't successful, or if the baby moves back into a breech position, talk with a member of your health care team about the choices you have for delivery. Many babies in a complete or incomplete breech position are born by planned C-section.

When a baby is sideways — lying horizontal across the uterus, rather than vertical — it's called a transverse lie. In this position, the baby's back might be:

• Down, with the back facing the birth canal.
• Sideways, with one shoulder pointing toward the birth canal.
• Up, with the hands and feet facing the birth canal.

Although many babies are sideways early in pregnancy, few stay this way when labor begins.

If your baby is in a transverse lie during week 37 of your pregnancy, your health care professional may try to move the baby into a head-down position. This is done using a procedure called external cephalic version. External cephalic version involves one or two members of your health care team putting pressure on your belly with their hands to get the baby to roll into a head-down position.

If the procedure isn't successful, or if the baby moves back into a transverse lie, talk with a member of your health care team about the choices you have for delivery. Many babies who are in a transverse lie are born by C-section.

If you're pregnant with twins and only the twin that's lower in the uterus is head down, as shown below, your health care provider may first deliver that baby vaginally.

Then, in some cases, your health care team may suggest delivering the second twin in the breech position. Or they may try to move the second twin into a head-down position. This is done using a procedure called external cephalic version. External cephalic version involves one or two members of the health care team putting pressure on your belly with their hands to get the baby to roll into a head-down position.

Your health care team may suggest delivery by C-section for the second twin if:

• An attempt to deliver the baby in the breech position is not successful.
• You do not want to try to have the baby delivered vaginally in the breech position.
• An attempt to move the baby into a head-down position is not successful.
• You do not want to try to move the baby to a head-down position.

In some cases, your health care team may advise that you have both twins delivered by C-section. That might happen if the lower twin is not head down, the second twin has low or high birth weight as compared to the first twin, or if preterm labor starts.

• Landon MB, et al., eds. Normal labor and delivery. In: Gabbe's Obstetrics: Normal and Problem Pregnancies. 8th ed. Elsevier; 2021. https://www.clinicalkey.com. Accessed May 19, 2023.
• Holcroft Argani C, et al. Occiput posterior position. https://www.updtodate.com/contents/search. Accessed May 19, 2023.
• Frequently asked questions: If your baby is breech. American College of Obstetricians and Gynecologists https://www.acog.org/womens-health/faqs/if-your-baby-is-breech. Accessed May 22, 2023.
• Hofmeyr GJ. Overview of breech presentation. https://www.updtodate.com/contents/search. Accessed May 22, 2023.
• Strauss RA, et al. Transverse fetal lie. https://www.updtodate.com/contents/search. Accessed May 22, 2023.
• Chasen ST, et al. Twin pregnancy: Labor and delivery. https://www.updtodate.com/contents/search. Accessed May 22, 2023.
• Cohen R, et al. Is vaginal delivery of a breech second twin safe? A comparison between delivery of vertex and non-vertex second twins. The Journal of Maternal-Fetal & Neonatal Medicine. 2021; doi:10.1080/14767058.2021.2005569.
• Marnach ML (expert opinion). Mayo Clinic. May 31, 2023.

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Breech presentation

Highlights & basics, diagnostic approach, risk factors, history & exam, differential diagnosis.

• Tx Approach

Emerging Tx

Complications.

PATIENT RESOURCES

Patient Instructions

Breech presentation refers to the baby presenting for delivery with the buttocks or feet first rather than head.

Associated with increased morbidity and mortality for the mother in terms of emergency cesarean section and placenta previa; and for the baby in terms of preterm birth, small fetal size, congenital anomalies, and perinatal mortality.

Incidence decreases as pregnancy progresses and by term occurs in 3% to 4% of singleton term pregnancies.

Treatment options include external cephalic version to increase the likelihood of vaginal birth or a planned cesarean section, the optimal gestation being 37 and 39 weeks, respectively.

Planned cesarean section is considered the safest form of delivery for infants with a persisting breech presentation at term.

Quick Reference

Key Factors

buttocks or feet as the presenting part

Fetal head under costal margin, fetal heartbeat above the maternal umbilicus.

Other Factors

subcostal tenderness

Pelvic or bladder pain.

Diagnostics Tests

1st Tests to Order

transabdominal/transvaginal ultrasound

Treatment options.

presumptive

<37 weeks' gestation

specialist evaluation

corticosteroid

magnesium sulfate

≥37 weeks' gestation not in labor

unsuccessful ECV with persistent breech

Classifications

Types of breech presentation

Baby's buttocks lead the way into the birth canal

Hips are flexed, knees are extended, and the feet are in close proximity to the head

65% to 70% of breech babies are in this position.

Baby presents with buttocks first

Both the hips and the knees are flexed; the baby may be sitting cross-legged.

One or both of the baby's feet lie below the breech so that the foot or knee is lowermost in the birth canal

This is rare at term but relatively common with premature fetuses.

Common Vignette

Other Presentations

Epidemiology

33% of births less than 28 weeks' gestation

14% of births at 29 to 32 weeks' gestation

9% of births at 33 to 36 weeks' gestation

6% of births at 37 to 40 weeks' gestation.

Pathophysiology

• Natasha Nassar, PhD
• Christine L. Roberts, MBBS, FAFPHM, DrPH
• Jonathan Morris, MBChB, FRANZCOG, PhD
• John W. Bachman, MD
• Rhona Hughes, MBChB
• Brian Peat, MD
• Lelia Duley, MBChB
• Justus Hofmeyr, MD

Clinical exam

Palpation of the abdomen to determine the position of the baby's head

Palpation of the abdomen to confirm the position of the fetal spine on one side and fetal extremities on the other

Palpation of the area above the symphysis pubis to locate the fetal presenting part

Palpation of the presenting part to confirm presentation, to determine how far the fetus has descended and whether the fetus is engaged.

Ultrasound examination

Premature fetus.

Prematurity is consistently associated with breech presentation. [ 6 ] [ 9 ] This may be due to the smaller size of preterm infants, who are more likely to change their in utero position.

Increasing duration of pregnancy may allow breech-presenting fetuses time to grow, turn spontaneously or by external cephalic version, and remain cephalic-presenting.

Larger fetuses may be forced into a cephalic presentation in late pregnancy due to space or alignment constraints within the uterus.

small for gestational age fetus

Low birth-weight is a risk factor for breech presentation. [ 9 ] [ 11 ] [ 12 ] [ 13 ] [ 14 ] Term breech births are associated with a smaller fetal size for gestational age, highlighting the association with low birth-weight rather than prematurity. [ 6 ]

nulliparity

Women having a first birth have increased rates of breech presentation, probably due to the increased likelihood of smaller fetal size. [ 6 ] [ 9 ]

Relaxation of the uterine wall in multiparous women may reduce the odds of breech birth and contribute to a higher spontaneous or external cephalic version rate. [ 10 ]

fetal congenital anomalies

Congenital anomalies in the fetus may result in a small fetal size or inappropriate fetal growth. [ 9 ] [ 12 ] [ 14 ] [ 15 ]

Anencephaly, hydrocephaly, Down syndrome, and fetal neuromuscular dysfunction are associated with breech presentation, the latter due to its effect on the quality of fetal movements. [ 9 ] [ 14 ]

previous breech delivery

The risk of recurrent breech delivery is 8%, the risk increasing from 4% after one breech delivery to 28% after three. [ 16 ]

The effects of recurrence may be due to recurring specific causal factors, either genetic or environmental in origin.

uterine abnormalities

Women with uterine abnormalities have a high incidence of breech presentation. [ 14 ] [ 17 ] [ 18 ] [ 19 ]

female fetus

Fifty-four percent of breech-presenting fetuses are female. [ 14 ]

abnormal amniotic fluid volume

Both oligohydramnios and polyhydramnios are associated with breech presentation. [ 1 ] [ 12 ] [ 14 ]

Low amniotic fluid volume decreases the likelihood of a fetus turning to a cephalic position; an increased amniotic fluid volume may facilitate frequent change in position.

placental abnormalities

An association between placental implantation in the cornual-fundal region and breech presentation has been reported, although some studies have not found it a risk factor. [ 8 ] [ 20 ] [ 21 ] [ 22 ] [ 10 ] [ 14 ]

The association with placenta previa is also inconsistent. [ 8 ] [ 9 ] [ 22 ] Placenta previa is associated with preterm birth and may be an indirect risk factor.

Pelvic or vaginal examination reveals the buttocks and/or feet, felt as a yielding, irregular mass, as the presenting part. [ 26 ] In cephalic presentation, a hard, round, regular fetal head can be palpated. [ 26 ]

The Leopold maneuver on examination suggests breech position by palpation of the fetal head under the costal margin. [ 26 ]

The baby's heartbeat should be auscultated using a Pinard stethoscope or a hand-held Doppler to indicate the position of the fetus. The fetal heartbeat lies above the maternal umbilicus in breech presentation. [ 1 ]

Tenderness under one or other costal margin as a result of pressure by the harder fetal head.

Pain due to fetal kicks in the maternal pelvis or bladder.

breech position

Visualizes the fetus and reveals its position.

Used to confirm a clinically suspected breech presentation. [ 28 ]

Should be performed by practitioners with appropriate skills in obstetric ultrasound.

Establishes the type of breech presentation by imaging the fetal femurs and their relationship to the distal bones.

Transverse lie

Differentiating Signs/Symptoms

Fetus lies horizontally across the uterus with the shoulder as the presenting part.

Similar predisposing factors such as placenta previa, abnormal amniotic fluid volume, and uterine anomalies, although more common in multiparity. [ 1 ] [ 2 ] [ 29 ]

Differentiating Tests

Clinical examination and fetal auscultation may be indicative.

Ultrasound confirms presentation.

Treatment Approach

Breech presentation <37 weeks' gestation.

The UK Royal College of Obstetricians and Gynaecologists (RCOG) recommends that corticosteroids should be offered to women between 24 and 34+6 weeks' gestation, in whom imminent preterm birth is anticipated. Corticosteroids should only be considered after discussion of risks/benefits at 35 to 36+6 weeks. Given within 7 days of preterm birth, corticosteroids may reduce perinatal and neonatal death and respiratory distress syndrome. [ 32 ] The American College of Obstetricians and Gynecologists (ACOG) recommends a single course of corticosteroids for pregnant women between 24 and 33+6 weeks' gestation who are at risk of preterm delivery within 7 days, including those with ruptured membranes and multiple gestations. It may also be considered for pregnant women starting at 23 weeks' gestation who are at risk of preterm delivery within 7 days. A single course of betamethasone is recommended for pregnant women between 34 and 36+6 weeks' gestation at risk of preterm birth within 7 days, and who have not received a previous course of prenatal corticosteroids. Regularly scheduled repeat courses or serial courses (more than two) are not currently recommended. A single repeat course of prenatal corticosteroids should be considered in women who are less than 34 weeks' gestation, who are at risk of preterm delivery within 7 days, and whose prior course of prenatal corticosteroids was administered more than 14 days previously. Rescue course corticosteroids could be provided as early as 7 days from the prior dose, if indicated by the clinical scenario. [ 33 ]

Magnesium sulfate given before anticipated early preterm birth reduces the risk of cerebral palsy in surviving infants. Physicians electing to use magnesium sulfate for fetal neuroprotection should develop specific guidelines regarding inclusion criteria, treatment regimens, and concurrent tocolysis. [ 34 ]

Breech presentation from 37 weeks' gestation, before labor

ECV is the initial treatment for a breech presentation at term when the patient is not in labor. It involves turning a fetus presenting by the breech to a cephalic (head-down) presentation to increase the likelihood of vaginal birth. [ 35 ] [ 36 ] Where available, it should be offered to all women in late pregnancy, by an experienced clinician, in hospitals with facilities for emergency delivery, and no contraindications to the procedure. [ 35 ] There is no upper time limit on the appropriate gestation for ECV, with success reported at 42 weeks.

There is no general consensus on contraindications to ECV. Contraindications include multiple pregnancy (except after delivery of a first twin), ruptured membranes, current or recent (<1 week) vaginal bleeding, rhesus isoimmunization, other indications for cesarean section (e.g., placenta previa or uterine malformation), or abnormal electronic fetal monitoring. [ 35 ] One systematic review of relative contraindications for ECV highlighted that most contraindications do not have clear empirical evidence. Exceptions include placental abruption, severe preeclampsia/HELLP syndrome, or signs of fetal distress (abnormal cardiotocography and/or Doppler flow). [ 36 ]

The procedure involves applying external pressure and firmly pushing or palpating the mother's abdomen to coerce the fetus to somersault (either forward or backward) into a cephalic position. [ 37 ]

The overall ECV success rate varies but, in a large series, 47% of women following an ECV attempt had a cephalic presentation at birth. [ 35 ] [ 38 ]  Various factors influence the success rate. One systematic review found ECV success rates to be 68% overall, with the rate significantly higher for women from African countries (89%) compared with women from non-African countries (62%), and higher among multiparous (78%) than nulliparous women (48%). [ 39 ] Overall, the ECV success rates for nulliparous and multiparous non-African women were 43% and 73%, respectively, while for nulliparous and multiparous African women rates were 79% and 91%, respectively. Another study reported no difference in success rate or rate of cesarean section among women with previous cesarean section undergoing ECV compared with women with previous vaginal birth. However, numbers were small and further studies in this regard are required. [ 40 ]

Women's preference for vaginal delivery is a major contributing factor in their decision for ECV. However, studies suggest women with a breech presentation at term may not receive complete and/or evidence-based information about the benefits and risks of ECV. [ 41 ] [ 42 ] Although up to 60% of women reported ECV to be painful, the majority highlighted the benefits outweigh the risks (71%) and would recommend ECV to their friends or be willing to repeat for themselves (84%). [ 41 ] [ 42 ]

Cardiotocography and ultrasound should be performed before and after the procedure. Tocolysis should be used to facilitate the maneuver, and Rho(D) immune globulin should be administered to women who are Rhesus negative. [ 35 ] Tocolytic agents include adrenergic beta-2 receptor stimulants such as albuterol, terbutaline, or ritodrine (widely used with ECV in some countries, but not yet available in the US). One Cochrane review of tocolytic beta stimulants demonstrates that these are less likely to be associated with failed ECV, and are effective in increasing cephalic presentation and reducing cesarean section. [ 43 ] There is no current evidence to recommend one beta-2 adrenergic receptor agonist over another. Until these data are available, adherence to a local protocol for tocolysis is recommended. The Food and Drug Administration has issued a warning against using injectable terbutaline beyond 48 to 72 hours, or acute or prolonged treatment with oral terbutaline, in pregnant women for the prevention or prolonged treatment of preterm labor, due to potential serious maternal cardiac adverse effects and death. [ 44 ] Whether this warning applies to the subcutaneous administration of terbutaline in ECV is still unclear; however, studies currently support this use. The European Medicines Agency (EMA) recommends that injectable beta agonists should be used for up to 48 hours between the 22nd and 37th week of pregnancy only. They should be used under specialist supervision with continuous monitoring of the mother and unborn baby owing to the risk of adverse cardiovascular effects in both the mother and baby. The EMA no longer recommends oral or rectal formulations for obstetric indications. [ 45 ]

If ECV is successful, pregnancy care should continue as usual for any cephalic presentation. One systematic review assessing the mode of delivery after a successful ECV found that these women were at increased risk for cesarean section and instrumental vaginal delivery compared with women with spontaneous cephalic pregnancies. However, they still had a lower rate of cesarean section following ECV (i.e., 47%) compared with the cesarean section rate for those with a persisting breech (i.e., 85%). With a number needed to treat of three, ECV is still considered to be an effective means of preventing the need for cesarean section. [ 46 ]

Planned cesarean section should be offered as the safest mode of delivery for the baby, even though it carries a small increase in serious immediate maternal complications compared with vaginal birth. [ 24 ] [ 25 ] [ 31 ] In the US, most unsuccessful ECV with persistent breech will be delivered via cesarean section.

A vaginal mode of delivery may be considered by some clinicians as an option, particularly when maternal request is provided, senior and experienced staff are available, there is no absolute contraindication to vaginal birth (e.g., placenta previa, compromised fetal condition), and with optimal fetal growth (estimated weight above the tenth centile and up to 3800 g). Other factors that make planned vaginal birth higher risk include hyperextended neck on ultrasound and footling presentation. [ 24 ]

Breech presentation from 37 weeks' gestation, during labor

The first option should be a planned cesarean section.

There is a small increase in the risk of serious immediate maternal complications compared with vaginal birth (RR 1.29, 95% CI 1.03 to 1.61), including pulmonary embolism, infection, bleeding, damage to the bladder and bowel, slower recovery from the delivery, longer hospitalization, and delayed bonding and breast-feeding. [ 23 ] [ 31 ] [ 47 ] [ 48 ] [ 49 ] [ 50 ] [ 51 ] [ 52 ] [ 53 ] [ 54 ] [ 55 ] [ 56 ] [ 57 ] [ 58 ] Consider using antimicrobial triclosan-coated sutures for wound closure to reduce the risk of surgical site infection. [ 59 ]

The long-term risks include potential compromise of future obstetric performance, increased risk of repeat cesarean section, infertility, uterine rupture, placenta accreta, placental abruption, and emergency hysterectomy. [ 60 ] [ 61 ] [ 62 ] [ 63 ]

Planned cesarean section is safer for babies, but is associated with increased neonatal respiratory distress. The risk is reduced when the section is performed at 39 weeks' gestation. [ 64 ] [ 65 ] [ 66 ] For women undergoing a planned cesarean section, RCOG recommends an informed discussion about the potential risks and benefits of a course of prenatal corticosteroids between 37 and 38+6 weeks' gestation. Although prenatal corticosteroids may reduce admission to the neonatal unit for respiratory morbidity, it is uncertain if there is any reduction in respiratory distress syndrome, transient tachypnea of the newborn, or neonatal unit admission overall. In addition, prenatal corticosteroids may result in harm to the neonate, including hypoglycemia and potential developmental delay. [ 32 ] ACOG does not recommend corticosteroids in women >37 weeks' gestation. [ 33 ]

Undiagnosed breech in labor generally results in cesarean section after the onset of labor, higher rates of emergency cesarean section associated with the least favorable maternal outcomes, a greater likelihood of cord prolapse, and other poor infant outcomes. [ 23 ] [ 67 ] [ 49 ] [ 68 ] [ 69 ] [ 70 ] [ 71 ]

This mode of delivery may be considered by some clinicians as an option for women who are in labor, particularly when delivery is imminent. Vaginal breech delivery may also be considered, where suitable, when delivery is not imminent, maternal request is provided, senior and experienced staff are available, there is no absolute contraindication to vaginal birth (e.g., placenta previa, compromised fetal condition), and with optimal fetal growth (estimated weight above the tenth centile and up to 3800 g). Other factors that make planned vaginal birth higher risk include hyperextended neck on ultrasound and footling presentation. [ 24 ]

Findings from one systematic review of 27 observational studies revealed that the absolute risks of perinatal mortality, fetal neurologic morbidity, birth trauma, 5-minute Apgar score <7, and neonatal asphyxia in the planned vaginal delivery group were low at 0.3%, 0.7%, 0.7%, 2.4%, and 3.3%, respectively. However, the relative risks of perinatal mortality and morbidity were 2- to 5-fold higher in the planned vaginal than in the planned cesarean delivery group. Authors recommend ongoing judicious decision-making for vaginal breech delivery for selected singleton, term breech babies. [ 72 ]

ECV may also be considered an option for women with breech presentation in early labor, when delivery is not imminent, provided that the membranes are intact.

A woman presenting with a breech presentation <37 weeks is an area of clinical controversy. Optimal mode of delivery for preterm breech has not been fully evaluated in clinical trials, and the relative risks for the preterm infant and mother remain unclear. In the absence of good evidence, if diagnosis of breech presentation prior to 37 weeks' gestation is made, prematurity and clinical circumstances should determine management and mode of delivery.

Primary Options

12 mg intramuscularly every 24 hours for 2 doses

6 mg intramuscularly every 12 hours for 4 doses

The UK Royal College of Obstetricians and Gynaecologists recommends that corticosteroids should be offered to women between 24 and 34+6 weeks' gestation, in whom imminent preterm birth is anticipated. Corticosteroids should only be considered after discussion of risks/benefits at 35 to 36+6 weeks. Given within 7 days of preterm birth, corticosteroids may reduce perinatal and neonatal death and respiratory distress syndrome. [ 32 ]

The American College of Obstetricians and Gynecologists recommends a single course of corticosteroids for pregnant women between 24 and 33+6 weeks' gestation who are at risk of preterm delivery within 7 days, including those with ruptured membranes and multiple gestations. It may also be considered for pregnant women starting at 23 weeks' gestation who are at risk of preterm delivery within 7 days. A single course of betamethasone is recommended for pregnant women between 34 and 36+6 weeks' gestation at risk of preterm birth within 7 days, and who have not received a previous course of prenatal corticosteroids. Regularly scheduled repeat courses or serial courses (more than two) are not currently recommended. A single repeat course of prenatal corticosteroids should be considered in women who are less than 34 weeks' gestation, who are at risk of preterm delivery within 7 days, and whose prior course of prenatal corticosteroids was administered more than 14 days previously. Rescue course corticosteroids could be provided as early as 7 days from the prior dose, if indicated by the clinical scenario. [ 33 ]

consult specialist for guidance on dose

external cephalic version (ECV)

There is no upper time limit on the appropriate gestation for ECV; it should be offered to all women in late pregnancy by an experienced clinician in hospitals with facilities for emergency delivery and no contraindications to the procedure. [ 35 ] [ 36 ]

ECV involves applying external pressure and firmly pushing or palpating the mother's abdomen to coerce the fetus to somersault (either forward or backward) into a cephalic position. [ 37 ]

There is no general consensus on contraindications to ECV. Contraindications include multiple pregnancy (except after delivery of a first twin), ruptured membranes, current or recent (<1 week) vaginal bleeding, rhesus isoimmunization, other indications for cesarean section (e.g., placenta previa or uterine malformation), or abnormal electronic fetal monitoring. [ 35 ]  One systematic review of relative contraindications for ECV highlighted that most contraindications do not have clear empirical evidence. Exceptions include placental abruption, severe preeclampsia/HELLP syndrome, or signs of fetal distress (abnormal cardiotocography and/or Doppler flow). [ 36 ]

Cardiotocography and ultrasound should be performed before and after the procedure.

If ECV is successful, pregnancy care should continue as usual for any cephalic presentation. A systematic review assessing the mode of delivery after a successful ECV found that these women were at increased risk for cesarean section and instrumental vaginal delivery compared with women with spontaneous cephalic pregnancies. However, they still had a lower rate of cesarean section following ECV (i.e., 47%) compared with the cesarean section rate for those with a persisting breech (i.e., 85%). With a number needed to treat of 3, ECV is still considered to be an effective means of preventing the need for cesarean section. [ 46 ]

tocolytic agents

see local specialist protocol for dosing guidelines

Tocolytic agents include adrenergic beta-2 receptor stimulants such as albuterol, terbutaline, or ritodrine (widely used with external cephalic version [ECV] in some countries, but not yet available in the US). They are used to delay or inhibit labor and increase the success rate of ECV. There is no current evidence to recommend one beta-2 adrenergic receptor agonist over another. Until these data are available, adherence to a local protocol for tocolysis is recommended.

The Food and Drug Administration has issued a warning against using injectable terbutaline beyond 48-72 hours, or acute or prolonged treatment with oral terbutaline, in pregnant women for the prevention or prolonged treatment of preterm labor, due to potential serious maternal cardiac adverse effects and death. [ 44 ] Whether this warning applies to the subcutaneous administration of terbutaline in ECV is still unclear; however, studies currently support this use. The European Medicines Agency (EMA) recommends that injectable beta agonists should be used for up to 48 hours between the 22nd and 37th week of pregnancy only. They should be used under specialist supervision with continuous monitoring of the mother and unborn baby owing to the risk of adverse cardiovascular effects in both the mother and baby. The EMA no longer recommends oral or rectal formulations for obstetric indications. [ 45 ]

A systematic review found there was no evidence to support the use of nifedipine for tocolysis. [ 73 ]

There is insufficient evidence to evaluate other interventions to help ECV, such as fetal acoustic stimulation in midline fetal spine positions, or epidural or spinal analgesia. [ 43 ]

Rho(D) immune globulin

300 micrograms intramuscularly as a single dose

Nonsensitized Rh-negative women should receive Rho(D) immune globulin. [ 35 ]

The indication for its administration is to prevent rhesus isoimmunization, which may affect subsequent pregnancy outcomes.

Rho(D) immune globulin needs to be given at the time of external cephalic version and should be given again postpartum to those women who give birth to an Rh-positive baby. [ 74 ]

It is best administered as soon as possible after the procedure, usually within 72 hours.

Dose depends on brand used. Dose given below pertains to most commonly used brands. Consult specialist for further guidance on dose.

elective cesarean section/vaginal breech delivery

Mode of delivery (cesarean section or vaginal breech delivery) should be based on the experience of the attending clinician, hospital policies, maternal request, and the presence or absence of complicating factors. In the US, most unsuccessful external cephalic version (ECV) with persistent breech will be delivered via cesarean section.

Cesarean section, at 39 weeks or greater, has been shown to significantly reduce perinatal mortality and neonatal morbidity compared with vaginal breech delivery (RR 0.33, 95% CI 0.19 to 0.56). [ 31 ] Although safer for these babies, there is a small increase in serious immediate maternal complications compared with vaginal birth (RR 1.29, 95% CI 1.03 to 1.61), as well as long-term risks for future pregnancies, including pulmonary embolism, bleeding, infection, damage to the bladder and bowel, slower recovery from the delivery, longer hospitalization, and delayed bonding and breast-feeding. [ 23 ] [ 31 ] [ 47 ] [ 48 ] [ 49 ] [ 50 ] [ 51 ] [ 52 ] [ 53 ] [ 54 ] [ 55 ] [ 56 ] [ 57 ] [ 58 ] Consider using antimicrobial triclosan-coated sutures for wound closure to reduce the risk of surgical site infection. [ 59 ]

Vaginal delivery may be considered by some clinicians as an option, particularly when maternal request is provided, when senior and experienced staff are available, when there is no absolute contraindication to vaginal birth (e.g., placenta previa, compromised fetal condition), and with optimal fetal growth (estimated weight above the tenth centile and up to 3800 g). Other factors that make planned vaginal birth higher risk include hyperextended neck on ultrasound and footling presentation. [ 24 ]

For women undergoing a planned cesarean section, the UK Royal College of Obstetricians and Gynaecologists recommends an informed discussion about the potential risks and benefits of a course of prenatal corticosteroids between 37 and 38+6 weeks' gestation. Although prenatal corticosteroids may reduce admission to the neonatal unit for respiratory morbidity, it is uncertain if there is any reduction in respiratory distress syndrome, transient tachypnea of the newborn, or neonatal unit admission overall. In addition, prenatal corticosteroids may result in harm to the neonate, including hypoglycemia and potential developmental delay. [ 32 ] The American College of Obstetricians and Gynecologists does not recommend corticosteroids in women >37 weeks' gestation. [ 33 ]

It is best administered as soon as possible after delivery, usually within 72 hours.

Administration of postpartum Rho (D) immune globulin should not be affected by previous routine prenatal prophylaxis or previous administration for a potentially sensitizing event. [ 74 ]

≥37 weeks' gestation in labor: no imminent delivery

planned cesarean section

For women with breech presentation in labor, planned cesarean section at 39 weeks or greater has been shown to significantly reduce perinatal mortality and neonatal morbidity compared with vaginal breech delivery (RR 0.33, 95% CI 0.19 to 0.56). [ 31 ]

Although safer for these babies, there is a small increase in serious immediate maternal complications compared with vaginal birth (RR 1.29, 95% CI 1.03 to 1.61), as well as long-term risks for future pregnancies, including pulmonary embolism, infection, bleeding, damage to the bladder and bowel, slower recovery from the delivery, longer hospitalization, and delayed bonding and breast-feeding. [ 23 ] [ 31 ] [ 47 ] [ 48 ] [ 49 ] [ 50 ] [ 51 ] [ 52 ] [ 53 ] [ 54 ] [ 55 ] [ 56 ] [ 57 ] [ 58 ]  Consider using antimicrobial triclosan-coated sutures for wound closure to reduce the risk of surgical site infection. [ 59 ]

Continuous cardiotocography monitoring should continue until delivery. [ 24 ] [ 25 ]

vaginal breech delivery

Mode of delivery (cesarean section or vaginal breech delivery) should be based on the experience of the attending clinician, hospital policies, maternal request, and the presence or absence of complicating factors.

This mode of delivery may be considered by some clinicians as an option, particularly when maternal request is provided, when senior and experienced staff are available, when there is no absolute contraindication to vaginal birth (e.g., placenta previa, compromised fetal condition), and with optimal fetal growth (estimated weight above the tenth centile and up to 3800 g). Other factors that make planned vaginal birth higher risk include hyperextended neck on ultrasound and footling presentation. [ 24 ]

For women with persisting breech presentation, planned cesarean section has, however, been shown to significantly reduce perinatal mortality and neonatal morbidity compared with vaginal breech delivery (RR 0.33, 95% CI 0.19 to 0.56). [ 31 ]

ECV may also be considered an option for women with breech presentation in early labor, provided that the membranes are intact.

There is no upper time limit on the appropriate gestation for ECV. [ 35 ]

Involves applying external pressure and firmly pushing or palpating the mother's abdomen to coerce the fetus to somersault (either forward or backward) into a cephalic position. [ 37 ]

Relative contraindications include placental abruption, severe preeclampsia/HELLP syndrome, and signs of fetal distress (abnormal cardiotocography and/or abnormal Doppler flow). [ 35 ] [ 36 ]

Rho(D) immune globulin needs to be given at the time of ECV and should be given again postpartum to those women who give birth to an Rh-positive baby. [ 74 ]

≥37 weeks' gestation in labor: imminent delivery

cesarean section

For women with persistent breech presentation, planned cesarean section has been shown to significantly reduce perinatal mortality and neonatal morbidity compared with vaginal breech delivery (RR 0.33, 95% CI 0.19 to 0.56). [ 31 ] Although safer for these babies, there is a small increase in serious immediate maternal complications compared with vaginal birth (RR 1.29, 95% CI 1.03 to 1.61), as well as long-term risks for future pregnancies, including pulmonary embolism, infection, bleeding, damage to the bladder and bowel, slower recovery from the delivery, longer hospitalization, and delayed bonding and breast-feeding. [ 23 ] [ 31 ] [ 47 ] [ 48 ] [ 49 ] [ 50 ] [ 51 ] [ 52 ] [ 53 ] [ 54 ] [ 55 ] [ 56 ] [ 57 ] [ 58 ]  Consider using antimicrobial triclosan-coated sutures for wound closure to reduce the risk of surgical site infection. [ 59 ]

This mode of delivery may be considered by some clinicians as an option, particularly when delivery is imminent, maternal request is provided, when senior and experienced staff are available, when there is no absolute contraindication to vaginal birth (e.g., placenta previa, compromised fetal condition), and with optimal fetal growth (estimated weight above the tenth centile and up to 3800 g). Other factors that make planned vaginal birth higher risk include hyperextended neck on ultrasound and footling presentation. [ 24 ]

It is best administered as soon as possible after the delivery, usually within 72 hours.

External cephalic version before term

Moxibustion, postural management, follow-up overview, perinatal complications.

Compared with cephalic presentation, persistent breech presentation has increased frequency of cord prolapse, abruptio placentae, prelabor rupture of membranes, perinatal mortality, fetal distress (heart rate <100 bpm), preterm delivery, lower fetal weight. [ 10 ] [ 11 ] [ 67 ]

complications of cesarean section

There is a small increase in the risk of serious immediate maternal complications compared with vaginal birth (RR 1.29, 95% CI 1.03 to 1.61), including pulmonary embolism, infection, bleeding, damage to the bladder and bowel, slower recovery from the delivery, longer hospitalization, and delayed bonding and breast-feeding. [ 23 ] [ 31 ] [ 47 ] [ 48 ] [ 49 ] [ 50 ] [ 51 ] [ 52 ] [ 53 ] [ 54 ] [ 55 ] [ 56 ] [ 57 ] [ 58 ]

The long-term risks include potential compromise of future obstetric performance, increased risk of repeat cesarean section, infertility, uterine rupture, placenta accreta, placental abruption, and emergency hysterectomy. [ 60 ] [ 61 ] [ 62 ] [ 63 ] The evidence suggests that using sutures, rather than staples, for wound closure after cesarean section reduces the incidence of wound dehiscence. [ 59 ]

Emergency cesarean section, compared with planned cesarean section, has demonstrated a higher risk of severe obstetric morbidity, intra-operative complications, postoperative complications, infection, blood loss >1500 mL, fever, pain, tiredness, and breast-feeding problems. [ 23 ] [ 48 ] [ 50 ] [ 70 ] [ 81 ]

Key Articles

Impey LWM, Murphy DJ, Griffiths M, et al; Royal College of Obstetricians and Gynaecologists. Management of breech presentation: green-top guideline no. 20b. BJOG. 2017 Jun;124(7):e151-77. [Full Text]

Hofmeyr GJ, Hannah M, Lawrie TA. Planned caesarean section for term breech delivery. Cochrane Database Syst Rev. 2015 Jul 21;(7):CD000166. [Abstract] [Full Text]

Royal College of Obstetricians and Gynaecologists. External cephalic version and reducing the incidence of term breech presentation. March 2017 [internet publication]. [Full Text]

Cluver C, Gyte GM, Sinclair M, et al. Interventions for helping to turn term breech babies to head first presentation when using external cephalic version. Cochrane Database Syst Rev. 2015 Feb 9;(2):CD000184. [Abstract] [Full Text]

de Hundt M, Velzel J, de Groot CJ, et al. Mode of delivery after successful external cephalic version: a systematic review and meta-analysis. Obstet Gynecol. 2014 Jun;123(6):1327-34. [Abstract]

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Published by

American College of Obstetricians and Gynecologists

2016 (reaffirmed 2022)

Royal College of Obstetricians and Gynaecologists (UK)

National Institute for Health and Care Excellence (UK)

Topic last updated: 2024-03-05

Natasha Nassar , PhD

Associate Professor

Menzies Centre for Health Policy

Sydney School of Public Health

University of Sydney

Christine L. Roberts , MBBS, FAFPHM, DrPH

Research Director

Clinical and Population Health Division

Perinatal Medicine Group

Kolling Institute of Medical Research

Jonathan Morris , MBChB, FRANZCOG, PhD

Professor of Obstetrics and Gynaecology and Head of Department

Peer Reviewers

John W. Bachman , MD

Consultant in Family Medicine

Department of Family Medicine

Mayo Clinic

Rhona Hughes , MBChB

Lead Obstetrician

Lothian Simpson Centre for Reproductive Health

The Royal Infirmary

Brian Peat , MD

Director of Obstetrics

Women's and Children's Hospital

North Adelaide

South Australia

Lelia Duley , MBChB

Professor of Obstetric Epidemiology

University of Leeds

Bradford Institute of Health Research

Temple Bank House

Bradford Royal Infirmary

Justus Hofmeyr , MD

Head of the Department of Obstetrics and Gynaecology

East London Private Hospital

East London

South Africa

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Breech, posterior, transverse lie: What position is my baby in?

Fetal presentation, or how your baby is situated in your womb at birth, is determined by the body part that's positioned to come out first, and it can affect the way you deliver. At the time of delivery, 97 percent of babies are head-down (cephalic presentation). But there are several other possibilities, including feet or bottom first (breech) as well as sideways (transverse lie) and diagonal (oblique lie).

Fetal presentation and position

During the last trimester of your pregnancy, your provider will check your baby's presentation by feeling your belly to locate the head, bottom, and back. If it's unclear, your provider may do an ultrasound or an internal exam to feel what part of the baby is in your pelvis.

Fetal position refers to whether the baby is facing your spine (anterior position) or facing your belly (posterior position). Fetal position can change often: Your baby may be face up at the beginning of labor and face down at delivery.

Here are the many possibilities for fetal presentation and position in the womb.

Medical illustrations by Jonathan Dimes

Head down, facing down (anterior position)

A baby who is head down and facing your spine is in the anterior position. This is the most common fetal presentation and the easiest position for a vaginal delivery.

This position is also known as "occiput anterior" because the back of your baby's skull (occipital bone) is in the front (anterior) of your pelvis.

Head down, facing up (posterior position)

In the posterior position , your baby is head down and facing your belly. You may also hear it called "sunny-side up" because babies who stay in this position are born facing up. But many babies who are facing up during labor rotate to the easier face down (anterior) position before birth.

Posterior position is formally known as "occiput posterior" because the back of your baby's skull (occipital bone) is in the back (posterior) of your pelvis.

Frank breech

In the frank breech presentation, both the baby's legs are extended so that the feet are up near the face. This is the most common type of breech presentation. Breech babies are difficult to deliver vaginally, so most arrive by c-section .

Some providers will attempt to turn your baby manually to the head down position by applying pressure to your belly. This is called an external cephalic version , and it has a 58 percent success rate for turning breech babies. For more information, see our article on breech birth .

Complete breech

A complete breech is when your baby is bottom down with hips and knees bent in a tuck or cross-legged position. If your baby is in a complete breech, you may feel kicking in your lower abdomen.

Incomplete breech

In an incomplete breech, one of the baby's knees is bent so that the foot is tucked next to the bottom with the other leg extended, positioning that foot closer to the face.

Single footling breech

In the single footling breech presentation, one of the baby's feet is pointed toward your cervix.

Double footling breech

In the double footling breech presentation, both of the baby's feet are pointed toward your cervix.

Transverse lie

In a transverse lie, the baby is lying horizontally in your uterus and may be facing up toward your head or down toward your feet. Babies settle this way less than 1 percent of the time, but it happens more commonly if you're carrying multiples or deliver before your due date.

If your baby stays in a transverse lie until the end of your pregnancy, it can be dangerous for delivery. Your provider will likely schedule a c-section or attempt an external cephalic version , which is highly successful for turning babies in this position.

Oblique lie

In rare cases, your baby may lie diagonally in your uterus, with his rump facing the side of your body at an angle.

Like the transverse lie, this position is more common earlier in pregnancy, and it's likely your provider will intervene if your baby is still in the oblique lie at the end of your third trimester.

Was this article helpful?

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BabyCenter's editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world. When creating and updating content, we rely on credible sources: respected health organizations, professional groups of doctors and other experts, and published studies in peer-reviewed journals. We believe you should always know the source of the information you're seeing. Learn more about our editorial and medical review policies .

Ahmad A et al. 2014. Association of fetal position at onset of labor and mode of delivery: A prospective cohort study. Ultrasound in obstetrics & gynecology 43(2):176-182. https://www.ncbi.nlm.nih.gov/pubmed/23929533 Opens a new window [Accessed September 2021]

Gray CJ and Shanahan MM. 2019. Breech presentation. StatPearls.  https://www.ncbi.nlm.nih.gov/books/NBK448063/ Opens a new window [Accessed September 2021]

Hankins GD. 1990. Transverse lie. American Journal of Perinatology 7(1):66-70.  https://www.ncbi.nlm.nih.gov/pubmed/2131781 Opens a new window [Accessed September 2021]

Medline Plus. 2020. Your baby in the birth canal. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/002060.htm Opens a new window [Accessed September 2021]

Where to go next

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Open Access

Peer-reviewed

Research Article

Impact of point-of-care ultrasound and routine third trimester ultrasound on undiagnosed breech presentation and perinatal outcomes: An observational multicentre cohort study

Contributed equally to this work with: Samantha Knights, Smriti Prasad

Roles Data curation

Affiliation Department of Obstetrics and Gynaecology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, United Kingdom

Roles Conceptualization, Data curation, Writing – original draft, Writing – review & editing

Affiliation Fetal Medicine Unit, St George’s University Hospitals NHS Foundation Trust, London, United Kingdom

Roles Conceptualization, Formal analysis, Methodology, Supervision, Validation, Writing – original draft, Writing – review & editing

Affiliations Department of Statistics, Middle East Technical University, Faculty of Arts and Sciences, Ankara, Turkey, Department of Obstetrics and Gynaecology, Koc University, School of Medicine, Istanbul, Turkey

Roles Conceptualization

Roles Conceptualization, Writing – review & editing

Roles Conceptualization, Methodology, Supervision, Writing – original draft, Writing – review & editing

* E-mail: [email protected]

Affiliations Fetal Medicine Unit, St George’s University Hospitals NHS Foundation Trust, London, United Kingdom, Vascular Biology Research Centre, Molecular and Clinical Sciences Research Institute, St George’s University of London, London, United Kingdom, Fetal Medicine Unit, Liverpool Women’s Hospital, Liverpool, United Kingdom

• Samantha Knights, 
• Smriti Prasad, 
• Erkan Kalafat, 
• Anahita Dadali, 
• Pam Sizer, 
• Francoise Harlow, 
• Asma Khalil

• Published: April 6, 2023
• https://doi.org/10.1371/journal.pmed.1004192
• Peer Review
• Reader Comments

Accurate knowledge of fetal presentation at term is vital for optimal antenatal and intrapartum care. The primary objective was to compare the impact of routine third trimester ultrasound or point-of-care ultrasound (POCUS) with standard antenatal care, on the incidence of overall and proportion of all term breech presentations that were undiagnosed at term, and on the related adverse perinatal outcomes.

Methods and findings

This was a retrospective multicentre cohort study where we included data from St. George’s (SGH) and Norfolk and Norwich University Hospitals (NNUH). Pregnancies were grouped according to whether they received routine third trimester scan (SGH) or POCUS (NNUH). Women with multiple pregnancy, preterm birth prior to 37 weeks, congenital abnormality, and those undergoing planned cesarean section for breech presentation were excluded. Undiagnosed breech presentation was defined as follows: (a) women presenting in labour or with ruptured membranes at term subsequently discovered to have a breech presentation; and (b) women attending for induction of labour at term found to have a breech presentation before induction. The primary outcome was the proportion of all term breech presentations that were undiagnosed. The secondary outcomes included mode of birth, gestational age at birth, birth weight, incidence of emergency cesarean section, and the following neonatal adverse outcomes: Apgar score <7 at 5 minutes, unexpected neonatal unit (NNU) admission, hypoxic ischemic encephalopathy (HIE), and perinatal mortality (including stillbirths and early neonatal deaths). We employed a Bayesian approach using informative priors from a previous similar study; updating their estimates (prior) with our own data (likelihood). The association of undiagnosed breech presentation at birth with adverse perinatal outcomes was analyzed with Bayesian log-binomial regression models. All analyses were conducted using R for Statistical Software (v.4.2.0).

Before and after the implementation of routine third trimester scan or POCUS, there were 16,777 and 7,351 births in SGH and 5,119 and 4,575 in NNUH, respectively. The rate of breech presentation in labour was consistent across all groups (3% to 4%). In the SGH cohort, the percentage of all term breech presentations that were undiagnosed was 14.2% (82/578) before (years 2016 to 2020) and 2.8% (7/251) after (year 2020 to 2021) the implementation of universal screening ( p < 0.001). Similarly, in the NNUH cohort, the percentage of all term breech presentations that were undiagnosed was 16.2% (27/167) before (year 2015) and 3.5% (5/142) after (year 2020 to 2021) the implementation of universal POCUS screening ( p < 0.001). Bayesian regression analysis with informative priors showed that the rate of undiagnosed breech was 71% lower after the implementation of universal ultrasound (RR, 0.29; 95% CrI 0.20, 0.38) with a posterior probability greater than 99.9%. Among the pregnancies with breech presentation, there was also a very high probability (>99.9%) of reduced rate of low Apgar score (<7) at 5 minutes by 77% (RR, 0.23; 95% CrI 0.14, 0.38). There was moderate to high probability (posterior probability: 89.5% and 85.1%, respectively) of a reduction of HIE (RR, 0.32; 95% CrI 0.0.05, 1.77) and extended perinatal mortality rates (RR, 0.21; 95% CrI 0.01, 3.00). Using informative priors, the proportion of all term breech presentations that were undiagnosed was 69% lower after the initiation of universal POCUS (RR, 0.31; 95% CrI 0.21, 0.45) with a posterior probability greater of 99.9%. There was also a very high probability (99.5%) of a reduced rate of low Apgar score (<7) at 5 minutes by 40% (RR, 0.60; 95% CrI 0.39, 0.88). We do not have reliable data on number of facility-based ultrasound scans via the standard antenatal referral pathway or external cephalic versions (ECVs) performed during the study period.

Conclusions

In our study, we observed that both a policy of routine facility-based third trimester ultrasound or POCUS are associated with a reduction in the proportion of term breech presentations that were undiagnosed, with an improvement in neonatal outcomes. The findings from our study support the policy of third trimester ultrasound scan for fetal presentation. Future studies should focus on exploring the cost-effectiveness of POCUS for fetal presentation.

Author summary

Why was this study done.

• Accurate knowledge of fetal presentation is essential for optimal care during pregnancy and birth. Vaginal breech delivery is associated with adverse maternal and perinatal outcomes.
• Abdominal palpation has poor sensitivity (50% to 70%) for determination of fetal presentation.
• The role of a routine third ultrasound assessment of fetal presentation has been reported but the impact on neonatal outcomes is yet to be determined.
• There are limited reports on antenatal use of handheld point-of-care ultrasound (POCUS) for the determination of fetal presentation, but the impact of their systematic use for this purpose is largely unknown.

What did the researchers do and find?

• We analysed 2 cohorts of pregnant women from 2 large teaching hospitals in the United Kingdom where a policy of routine third trimester ultrasound or POCUS has been implemented.
• We studied the impact of routine third trimester ultrasound or POCUS on the percentage of all term breech presentations that were undiagnosed and adverse neonatal outcomes, in pre- and post-screening epochs.
• Due to the rarity of adverse outcomes, we employed Bayesian regression analysis with informative priors. This statistical tool permits updating previous findings with new data to generate new evidence.
• We found that the incidence of all term breech presentations that were undiagnosed reduced drastically in the post-screening epoch following the implementation of either a third trimester ultrasound (decreased from 14.2% to 2.8%) or POCUS (decreased from 16.2% to 3.5%). There was an associated improvement in neonatal outcomes.

What do these findings mean?

• Our findings imply that a policy of either a third trimester ultrasound by sonographers or POCUS by trained midwives was effective in reducing the proportion of all term breech presentations at the time of birth that were undiagnosed and associated neonatal complications.
• Cost-effectiveness of POCUS needs to be explored further for feasibility of implementation on a wider scale for assessment of fetal presentation at term.

Citation: Knights S, Prasad S, Kalafat E, Dadali A, Sizer P, Harlow F, et al. (2023) Impact of point-of-care ultrasound and routine third trimester ultrasound on undiagnosed breech presentation and perinatal outcomes: An observational multicentre cohort study. PLoS Med 20(4): e1004192. https://doi.org/10.1371/journal.pmed.1004192

Received: August 19, 2022; Accepted: February 7, 2023; Published: April 6, 2023

Copyright: © 2023 Knights et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: Data cannot be shared publicly because consent was not obtained from women; permission for sharing data was not sought as part of ethical approval. Data is only available following approval from Research Ethics Committee and Confidentiality Advisory Group. Enquiries and requests should be made to the the Research Governance and Delivery team at St George's University of London ( [email protected] ).

Funding: The author(s) received no specific funding for this work.

Competing interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: AK is a Vice President of the Royal College of Obstetricians and Gynaecologists. AK is a Trustee (and the Treasurer) of the International Society of Ultrasound in Obstetrics and Gynecology AK has lectured at and consulted in several ultrasound-based projects, webinars and educational events.

Abbreviations: BAME, black, Asian, and minority ethnic; BMI, body mass index; CrI, credible intervals; ECV, external cephalic version; HIE, hypoxic ischemic encephalopathy; HRA, Health Research Authority; HTA, Health Technology Assessment; IMD, index of multiple deprivation; NICE, National Institute for Health and Care Excellence; NIHR, National Institute for Health Research; NNU, neonatal unit; NNUH, Norfolk and Norwich University Hospital; NSC, National Screening Committee; POCUS, point-of-care ultrasound; RR, risk ratio; SGH, St. George’s Hospital

Introduction

The incidence of breech presentation at term is 3% to 4% [ 1 ]. Breech vaginal birth is associated with an increase in both perinatal mortality and morbidity as well as maternal morbidity [ 2 – 7 ]. Correct knowledge of fetal presentation at term is essential for providing optimum antepartum and intrapartum care. Women with breech presentation at term can be effectively counselled about their options—external cephalic version (ECV), planned vaginal birth, or elective cesarean birth—with their inherent risks and perceived benefits [ 1 ]. There is substantial evidence that clinical examination is not accurate enough for determination of fetal presentation, with unacceptably high rates of missed breech/noncephalic presentations at term [ 8 , 9 ].

There are 2 modalities to screen for fetal presentation at term, each with its advantages and disadvantages: routine third trimester ultrasound or point-of-care/portable ultrasound (POCUS). Currently, routine third trimester ultrasound is not recommended by the United Kingdom National Institute for Health and Care Excellence (NICE) in low-risk pregnancies due to insufficient clinical and cost-effectiveness evidence [ 10 , 11 ]. In the UK, the current practice is to perform an early pregnancy risk assessment followed by referral pathways for low-risk and high-risk women. These risks relate to maternal, fetal, and placental pathology but are unrelated to the risk of breech presentation at term. Women deemed to be at high risk are referred for an ultrasound scan at 28 weeks’ gestation for fetal biometry with or without additional follow-up ultrasound scans. Low-risk women are followed up with clinical assessment (serial measurement of symphysio-fundal height) and referred for third trimester ultrasound if fetal growth restriction is suspected or if it is difficult to perform clinical examination, as in women with high body mass index (BMI), multiple pregnancy, or multiple uterine fibroids, or there is clinical suspicion of noncephalic fetal presentation at term [ 12 – 14 ]. Emerging data from observational studies and a systematic review indicate that it is feasible to accurately diagnose fetal presentation at term by third trimester ultrasound, thereby reducing the proportion of all term breech presentations that were undiagnosed at the time of labour and birth [ 15 – 18 ]. The clinical end point of any study of the diagnosis of breech presentation at term would be an improvement in neonatal outcomes, associated with reduction in incidence of undiagnosed breech. Hitherto published literature, however, could not demonstrate a translation of increased antenatal diagnosis of breech presentation into a statistically significant improvement in neonatal outcomes, most likely owing to the rarity of adverse outcomes.

Most of the data on the use of POCUS in antenatal settings are from low-resource settings where there is inadequate access to ultrasound owing to both material and physical constraints; hence, the focus is on task-shifting of obstetric ultrasound from sonographers to primary care providers [ 19 , 20 ]. A recently published review reported improved diagnostic accuracy with POCUS compared to clinical examination only, for high-risk obstetric conditions including fetal malpresentation, albeit studies were heterogeneous and referred to varying standards [ 21 ]. The Society of Obstetricians and Gynaecologists of Canada identifies POCUS as a useful modality for timely determination of fetal presentation [ 22 ]. A retrospective criterion-based audit performed in one of our study hospitals demonstrated that the use of POCUS by midwives in the antenatal ward/labour ward was associated with identification of previously unrecognized breech presentation, thereby preventing inappropriate induction of labour [ 23 ]. A recent validation study of POCUS in obstetric care showed near perfect agreement for assessment of fetal presentation [95.6% agreement, Kappa −0.887, 95% CI (0.78 to 0.99)] when compared to routine ultrasound [ 24 ]. There is, however, scanty literature on the diagnostic accuracy of POCUS in antenatal care settings for assessment of fetal presentation, compared to standard antenatal care, i.e., routine abdominal palpation, with referral for ultrasound when there is clinical suspicion of breech presentation.

In our study, we aimed to compare the impact of routine third trimester ultrasound or POCUS with standard antenatal care, on the incidence of overall and proportion of all term breech presentations that were undiagnosed at term, and on the related adverse perinatal outcomes.

The study included data from St. George’s University Hospital NHS Foundation Trust (SGH) and Norfolk and Norwich University Hospital NHS Foundation Trust (NNUH). For both centres, pregnancies were grouped according to whether they received routine third trimester scan (SGH) or POCUS (NNUH).

Routine third trimester scan cohort

We included a cohort of pregnant women who gave birth between 4 April 2016 and 30 September 2021, at SGH, a large teaching hospital in South West London. The chosen starting point was the date when birth records were first systematically entered into the current electronic database. At SGH, a policy of routine third trimester (at 36 weeks) ultrasound scan by sonographers for all pregnant women has been implemented since January 2020; this includes assessment of fetal biometry, umbilical and middle cerebral artery Doppler, placental localization, amniotic fluid volume, and fetal presentation. Following a diagnosis of breech presentation during the ultrasound scan, women are counselled about their options: ECV, planned cesarean birth, or planned vaginal birth. If women declined ECV or if it was unsuccessful, they were offered elective cesarean delivery from 39 weeks of gestation. The population was divided into 2 study groups: Group 1 (women who were offered and accepted a routine third trimester scan) and Group 2 (women who received standard antenatal care in line with national guidance, without a routine third trimester scan).

POCUS cohort

The POCUS cohort included pregnant women from NNUH where a policy of routine POCUS at the 36-week antenatal visit was fully adopted from November 2020 following stage-wise implementation in 2016. The POCUS is performed by a midwife using Vscan Air (GE Healthcare). NNUH is a large teaching hospital with approximately 6,000 births per year, and approximately 250 midwives working across the hospital and community. We included 2 groups: a historical cohort of women who received routine care—abdominal palpation and referral for selective ultrasound on clinical suspicion of breech presentation (2015) and those who had POCUS at the 36- to 37-week visit (November 2020 to 2021). Through 2016 to November 2020, POCUS was variably used, either on the labour ward or via referral from community midwives, on clinical suspicion of noncephalic presentation, and these women were not included in this study.

Training of midwives for POCUS cohort

The midwives in NNUH underwent a structured 3-month training programme. The workshops consisted of daily handheld scanning sessions with an hour of dedicated lectures. The theoretical lectures were followed by practice on consenting women in the antenatal ward. All the trainee midwives maintained a competency logbook, detailing both successful and unsuccessful cases. Following the initial workshops, “midwife champions” were identified who were deemed competent or held other ultrasound qualifications and were suitable for cascade training. POCUS training was a part of preceptor ship training of newly qualified midwives, while midwives working in nonpermanent roles were supported and advised to work with one of the champions.

The primary outcome was the proportion of all term breech presentations that were undiagnosed. Undiagnosed breech presentation was defined as follows: (a) breech presentation after the onset of labour or rupture of membranes at term; and (b) breech presentation diagnosed immediately before commencing induction of labour. The secondary outcomes included mode of birth, gestational age at birth, birth weight, incidence of emergency cesarean section, and the following neonatal adverse outcomes: Apgar score <7 at 5 minutes, unexpected neonatal unit (NNU) admission, hypoxic ischemic encephalopathy (HIE) 1 to 3, and perinatal mortality (includes stillbirths and early neonatal deaths).

Women with multiple pregnancies, preterm birth <37 weeks, and congenital abnormalities were excluded. Pregnancies undergoing planned cesarean section for breech presentation were excluded from the analysis of the study outcomes, except for the neonatal outcomes. Maternal demographic characteristics, antenatal, intrapartum, and perinatal data were extracted from Euroking E3 maternity information system and Viewpoint database (ViewPoint 5.6.8.428, ViewPoint Bildverarbeitung GmbH, Weßling, Germany). Routinely collected clinical data were collated from electronic health records and were deemed not to require ethics approval or signed patient consent as per the Health Research Authority (HRA) decision tool.

Statistical analysis

Descriptive variables were compared with Wilcoxon-signed rank test, t test, or chi-squared test, where appropriate. An adequately powered analysis is not practically feasible due to rarity of adverse outcomes following breech delivery. Therefore, we employed a Bayesian approach using informative priors from a previous similar study; updating their estimates (prior) with our own data (likelihood) [ 18 ]. The association of undiagnosed breech presentation at birth with adverse perinatal outcomes was analyzed with Bayesian log-binomial regression models and reported as RR (risk ratios) with credible intervals (CrI). Informative priors ( N ~ μ, σ ) for population mean were derived from Salim and colleagues and a weakly informative prior (Student t , df = 3) for model intercept. Prior parameters were estimated by using the log-risk ratios and log-confidence intervals from Salim and colleagues, and in case an effect could not be estimated in the original study due to a no-event situation, we added a single event to the corresponding group and reestimated the risk ratios. Two Markov chains were run for 1,500 iterations after an initial 500 burn-in period. Posterior probabilities were calculated using the probability density function of normal distribution. A sensitivity analysis using flat priors (noninformative) was also undertaken to investigate the weight of informative prior on the posterior density. Number needed to treat for important outcomes was calculated using current population numbers without incorporating external data. Convergence was checked with trace plots. All analyses were conducted using R for Statistical Software (v.4.2.0) using “brms” and “its.analysis” packages [ 25 , 26 ]. This study is reported as per the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline ( S1 STROBE Checklist).

Study cohorts

In the SGH cohort, there were 24,128 singleton pregnancies during the eligibility period, of which 16,777 births were before the introduction of universal third trimester ultrasound scan and 7,351 after. Baseline characteristics of included pregnancies are presented in Table 1 . Women who gave birth before universal ultrasound scan were significantly younger (33.2 versus 35.7 years, p < 0.001), had similar BMI (25.6 versus 25.7 kg/m 2 , p = 0.194) and multiparity rate (49.6% [8,316/16,777] versus 49.2% [3,617/7,351], p = 0.612) compared to those who gave birth after. There was a slight drop in the proportion of births that were in women from black, Asian, and minority ethnic (BAME) background (39.3% [6,588/16,777] versus 37.9% [2,785/7,351], p = 0.044). The index of multiple deprivation (IMD) quintiles were similar between the 2 epochs ( p > 0.05 for all quintiles; Table 1 ), as was the total number of breech presentations at the time of birth (3.4% [578/16,777] versus 3.4% [251/7,351], p = 0.953), including all diagnosed and undiagnosed cases. A comparison of the baseline characteristics, as well as the gestational age at delivery in weeks and mode of birth of pregnancies with breech presentation at birth in the study epochs before and after the introduction of universal 36-week ultrasound scan is shown in Table 2 . Pregnancies with breech presentation at term were significantly more likely to be delivered by elective cesarean section (76.9% [193/251] versus 60.7% [351/278], p < 0.001) after compared to before the implementation of the universal 36-week ultrasound scan. Emergency cesarean section was lower (17.1% [43/251] versus 30.8% [178/578], p < 0.001) after compared to before the implementation of the universal 36-week ultrasound scan. A similar trend was noted for vaginal breech delivery ( Table 2 ). The gestational age at birth was 39.1 weeks in both groups with a mean difference of 1 day. Although the difference was statistically significant, it would be deemed clinically inconsequential.

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The percentage of all term breech presentations that were undiagnosed was 14.2% (82/578) before and 2.8% (7/251) after the implementation of universal screening ( p < 0.001) ( Table 3 ). The rate of elective cesarean delivery was higher during the universal scan epoch (13.0% [959/7,351] versus 12.0% [2,019/16,777], p = 0.029), while the emergency cesarean rate was lower (12.9% [2,169/16,777] versus 11.5% [845/7,351], p = 0.029) compared to the previous epoch. The total number of vaginal breech births reduced from 29 per 10,000 births to 20 per 10,000 births, but this difference did not reach statistical significance ( p = 0.276). A regression discontinuity (interrupted time series) analysis showed significant variation in the number of undiagnosed breech presentations between 2 epochs (before and after universal ultrasound, p < 0.001) ( Fig 1 ).

Dotted line represents the fitted regression curve with splines.

https://doi.org/10.1371/journal.pmed.1004192.g001

https://doi.org/10.1371/journal.pmed.1004192.t003

In the NNUH cohort, there were 9,694 singleton births during the eligibility period, of which 5,119 births were before the initiation of POCUS screening and 4,575 births after the complete implementation of POCUS. Women who gave birth before POCUS were significantly older (34.6 versus 31.6 years, p < 0.001) and had a lower BMI (25.6 versus 26.5 kg/m 2 , p < 0.001) than those who gave birth after. The percentage of all term breech presentations that were undiagnosed was 16.2% (27/167) before and 3.5% (5/142) after the implementation of universal POCUS screening ( p < 0.001) ( Table 4 ).

https://doi.org/10.1371/journal.pmed.1004192.t004

Perinatal outcomes

We analysed the SGH cohort using Bayesian regression analysis with both flat (noninformative) and informative priors (Using data from Salim and colleagues) [ 18 ]. Regression with informative priors showed the percentage of all term breech presentations that were undiagnosed was 71% lower after the implementation of universal ultrasound (RR, 0.29; 95% CrI 0.20, 0.38) with a posterior probability greater than 99.9% ( Table 3 ). Among the pregnancies with breech presentation, there was also a very high probability (>99.9%) of reduced rate of low Apgar score (<7) at 5 minutes by 77% (RR, 0.23; 95% CrI 0.14, 0.38). There was moderate to high probability (posterior probability: 89.5% and 85.1%, respectively) of a reduction of HIE (RR, 0.32; 95% CrI 0.05, 1.77) and extended perinatal mortality rates (RR, 0.21; 95% CrI 0.01, 3.00). Analysis using flat priors (noninformative) also showed that the percentage of all term breech presentations that were undiagnosed was 74% lower (RR, 0.26; 95% CrI 0.10, 0.59) with very high posterior probability of 99.8%. The reduction in low Apgar scores was also observed in flat prior analysis that corresponded to a 65% reduction (RR, 0.35; 95% CrI 0.06, 1.42) with a moderate to high probability (89.8%). The number needed to scan to prevent one case of undiagnosed breech presentation was 255 (95% CI: 192 to 376).

We analysed the NNUH cohort using the same methods. Using informative priors, the proportion of all term breech presentations that were undiagnosed was 69% lower after the initiation of universal POCUS (RR, 0.31; 95% CrI 0.21, 0.45) with a posterior probability greater of 99.9% ( Table 4 ). There was also a very high probability (99.5%) of a reduced rate of low Apgar score (<7) at 5 minutes by 40% (RR, 0.60; 95% CrI 0.39, 0.88). Flat prior analysis also showed that undiagnosed breech presentation was lower by 80% (RR, 0.20; 95% CrI: 0.07, 0.51) with very high posterior probability of 99.9%. No inference could be made for HIE or extended perinatal mortality as there were no events in either period.

In our study, use of a policy of either routine third trimester scan or routine third trimester POCUS was associated with a significant reduction in the proportion of all breech presentations that were undiagnosed at term, when compared to standard antenatal care. Short-term adverse perinatal outcomes, including NNU admission and low Apgar scores, were significantly lower for the pregnancies with diagnosed breech presentation at term following a policy for screening by either routine third trimester scan or POCUS. Previous studies were unable to study perinatal outcomes due to their small numbers.

Our cohorts are derived from real-world data from 2 large teaching hospitals in the UK. Much of the previously reported literature on use of third trimester ultrasound for diagnosis of breech presentation is from research settings with a dedicated breech clinic and available expertise and skills for manoeuvres like ECV and vaginal breech births. Conclusions from research settings may not be generalizable to clinical settings and may be prone to bias. Furthermore, our study is the first to compare the impact of POCUS with routine antenatal care for diagnosis of fetal presentation. Routine ultrasound scan is effective at reducing the proportion of all term breech presentations that were undiagnosed, but the clinical impact of this change is hard to assess owing to the rarity of adverse outcomes [ 18 ]. We employed a Bayesian approach using both informative priors from similar studies and flat priors as a sensitivity analysis that allowed us to estimate the effect of universal ultrasound in probabilistic terms without depending on P values.

There are some limitations to our study. Firstly, we did not have reliable data on ECV for both our cohorts. The universal scan might have implications, not just for babies that were breech at birth (e.g., ECV could be performed, which could lead to not being breech and therefore not being included in the outcomes, or some other benefit, or indeed, theoretically, harm). Salim and colleagues included all babies diagnosed as breech. The method employed by Salim and colleagues also has drawbacks as it did not include those undiagnosed before the universal scan. Nevertheless, it is unlikely to have had a substantial impact on our results given the low acceptance and variable success rates. This is reflected in the almost identical incidence of overall (undiagnosed and diagnosed) breech presentation before and after screening. Salim and colleagues also reported no difference in the rates of overall breech presentations despite systematic use of ECV with acceptance rates of as high as 80% [ 18 ]. Secondly, the number of adverse neonatal outcomes such as extended perinatal mortality and HIE were not sufficient to estimate an effect in the NNUH cohort. Finally, the maternity records at NNUH were uploaded on electronic database only from April 2015. Therefore, reliable data on demographic parameters like BMI, ethnicity, and IMD were not available for the first quarter of 2015. These factors, however, are unlikely to influence the results.

Our findings of a reduction in the proportion of all term breech presentations that were undiagnosed at term after implementation of routine third trimester scan resonates with those of Salim and colleagues, who reported a reduction from 22.3% to 4.7% following the introduction of universal third trimester scan, compared to standard antenatal care [ 18 ]. Yet there are no published data from the UK on the impact of routine POCUS on the reduction of the percentage of all term breech presentations that were undiagnosed at term. Observational studies from Kenya [ 19 ], Uganda [ 27 ], and Guatemala [ 28 ] have reported that midwives who underwent focused basic obstetric ultrasound training for 3 to 8 weeks were able to identify fetal presentation with high sensitivity and specificity. The proportion of all term breech presentations that were undiagnosed at term, however, could not be eliminated in both cohorts, with 7 and 5 such cases in the routine third trimester scan and POCUS cohorts, respectively. Most of these cases were a consequence of spontaneous version to breech from cephalic presentation in multiparous women. Salim and colleagues also described spontaneous version to breech in multiparous women (76% of cases of undiagnosed breech) in their cohort. Wastlund and colleagues reported in their prospective cohort of 3,879 women that a policy of universal third trimester scan virtually eliminated undiagnosed breech presentations in labour [ 16 ]. It should, however, be noted that their cohort comprised of nulliparous women only in a strict research setting.

We also noted a significant improvement in short-term neonatal outcomes including low Apgar scores at 5 minutes and NNU admission. Salim and colleague demonstrated a nonsignificant improvement in short-term neonatal outcomes [ 18 ]. Although we were unable to demonstrate an effect on outcomes such as HIE and neonatal mortality, observational data from low-resource settings report a reduction in neonatal mortality when women were referred in a timely manner for fetal malpresentation [ 29 ].

Accurate knowledge of fetal presentation at term is crucial for optimal antenatal and intrapartum care. Both routine third trimester scan by a sonographer/clinician or use of POCUS by trained midwives can achieve this objective. Although evidence suggests that a planned breech vaginal birth may be offered after careful case selection and counselling, a large proportion of maternity units in the UK and worldwide lack skilled providers for vaginal breech births. Antenatal identification of breech presentation would allow healthcare providers to offer unbiased information such that pregnant women feel empowered to make an informed decision and have a positive birth experience. A meeting of the UK National Screening Committee (NSC) in March 2021 acknowledged that ultrasound for fetal presentation appears promising; however, the committee recommended that further work on screening for fetal presentation could not be commissioned at that time. The NSC agreed to add screening for fetal presentation to the recommendations list for reconsideration in 3 years’ time if significant evidence evolves in the interim [ 30 ]. Our findings add to that evidence base. A cost-effectiveness analysis study conducted in the UK showed that universal third trimester ultrasound would “virtually eliminate” the proportion of all term breech presentations that were undiagnosed and would be cost-effective if fetal presentation could be assessed at £19.80 pounds per woman or less [ 16 ]. A National Institute for Health Research (NIHR) Health Technology Assessment (HTA) review has suggested that handheld portable ultrasound can readily close this gap as a low-cost device that antenatal care providers like midwives could use for fetal presentation with minimal training [ 31 ]. The major obstacles to routine third trimester scan policy include the costs incurred, whereas a policy of using POCUS in community clinics and the labour ward by healthcare providers, after a short period of training, appears to be as effective as a policy of routine third trimester formal departmental ultrasound. Implementation of POCUS in the community for fetal presentation would also curtail indirect costs by reduction in referrals for facility-based ultrasound based on clinical suspicion, apart from also instilling a sense of empowerment among the care providers and satisfaction among pregnant women. The policy of POCUS was acceptable to pregnant women in our cohort who wanted to avoid nonessential hospital visits during the COVID-19 pandemic. A potential pitfall of the portable ultrasound cited when used in low-resource settings was dependence on internet coverage, which is unlikely to be a deterrent in the UK. Nonetheless, regular audits, ongoing training, and quality improvement measures should be in place to support community healthcare providers to ensure safe practice.

Our data suggest that a policy of either third trimester ultrasound or POCUS by healthcare providers could be effective in reducing the proportion of all term breech presentations that were undiagnosed at birth with an associated improvement in neonatal outcomes.

Supporting information

S1 strobe checklist. strobe checklist..

https://doi.org/10.1371/journal.pmed.1004192.s001

• 1. Management of Breech Presentation (Green-top Guideline No. 20b) [Internet]. Royal College of Obstetricians & Gynaecologists. [cited 2022 May 1]. Available from: https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg20b/
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• 11. National Guideline Alliance (UK). Identification of breech presentation: Antenatal care: Evidence review L [Internet]. London: National Institute for Health and Care Excellence (NICE); 2021 [cited 2022 May 1]. (NICE Evidence Reviews Collection). Available from: http://www.ncbi.nlm.nih.gov/books/NBK573936/
• 12. Overview | Antenatal care | Guidance | NICE [Internet]. NICE; [cited 2022 May 1]. Available from: https://www.nice.org.uk/guidance/ng201
• 13. Small-for-Gestational-Age Fetus, Investigation and Management (Green-top Guideline No. 31) [Internet]. Royal College of Obstetricians & Gynaecologists. [cited 2022 May 1]. Available from: https://www.rcog.org.uk/en/guidelines-research-services/guidelines/gtg31/
• 14. Perinatal Institute: Programme [Internet]. [cited 2022 May 1]. Available from: https://www.perinatal.org.uk/GAP/programme
• 23. British Journal of Midwifery—Detection of breech presentation: Abdominal palpation and hand-held scanning by midwives [Internet]. Br J Midwifery. [cited 2022 May 1]. Available from: https://www.britishjournalofmidwifery.com/articles/detection-of-breech-presentation-abdominal-palpation-and-hand-held-scanning-by-midwives/
• 26. English P The its.analysis R Package–Modelling Short Time Series Data (June 6, 2019). Available from: https://ssrn.com/abstract=3398189 . https://doi.org/10.2139/ssrn.3398189
• 30. UK NSC minutes March 2021 [Internet]. GOV.UK. [cited 2022 Jul 10]. Available from: https://www.gov.uk/government/publications/uk-nsc-meeting-march-2021/uk-nsc-minutes-march-2021
• 31. 21/582 Point of care ultrasound for breech presentation at term commissioning brief [Internet]. [cited 2022 May 1]. Available from: https://www.nihr.ac.uk/documents/21582-point-of-care-ultrasound-for-breech-presentation-at-term-commissioning-brief/29207

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Determining Normal Fetal Situs (Situs Solitus)

One of the first steps in obtaining cardiac views is to determine how the fetus is oriented within the uterus and to determine the right and left side of the abdominal contents versus the right and left side of the heart and thoracic contents.  This is not as easy as it might seem since the fetal left side can be on the maternal right and the opposite can be true.

In summary, situs refers to the right and left orientation of fetal organs.  For example situs solitus is the normal left to right axis arrangement in the fetus with the stomach and spleen on the left side of the body, and the liver and gallbladder on the right side.

Visual Summary of Normal Fetal Situs

Below are steps required to determine situs related to cephalic or breech presentation, and whether the spine or back is up (anterior) or down (posterior).

1.  Determine the lie of the fetus:

A.  Is the fetus head first with the head in front of the ultrasound screen?  This could also be termed cephalic or vertex presentation. B.  Is the fetal feet or bottom first with the head behind the screen?  This could also be termed footling or breech presentation. C.  Determine whether the spine or back is anterior (back up) or posterior (back down).

2.  Obtain a transverse cut of the thorax to demonstrate a 4-chamber view.  The left atrium is nearest the spine and the cardiac axis points to the left.

Detailed Method to Determine Fetal Situs

1.  Define within the uterus the presentation of the fetus (generally vertex or breech; less often the presentation is oblique or transverse.).

2.  Determine whether the fetal spine is parallel or transverse to the maternal spine.  In sagittal view, if the fetal and maternal spine are parallel, the fetus is in longitudinal lie.  When the fetal spine is perpendicular to the maternal spine, the fetus is in a transverse lie.

3.  Determine the position of the fetal left side.  The fetal left side will be as follows: A.  With respect to the maternal abdomen, the fetal left side is anterior and near to the ultrasound transducer. B.  With respect to the posterior uterine wall, the fetal left side is posterior and farthest from the transducer. C.  With respect to the right uterine wall, the fetal left side will be on the maternal right. D.  With respect to the left uterine wall, the fetal left side will be on the maternal left.

4.  Obtain a transverse view of the abdomen and define the fetal stomach which is positioned in the left side of the fetal abdomen.

5.  Obtain a 4-chamber view of the heart by obtaining a transverse view of the thorax.  The left atrium and descending aorta are nearest to the spine and the cardiac axis points to the left.

6.  Finally, ascertain if the stomach and heart are in their correct respective locations, i.e., the stomach is on the left side and the cardiac axis points to the left.

7.  Place a transverse image of the fetal abdomen and heart side by side and validate that the left side of the fetal abdomen (stomach near to the spine) is concordant with the left side of the fetal heart (left atrium and descending aorta near to the spine).  This is done by displaying a side by side comparison of a transverse view through the fetal stomach and a 4-chamber cardiac view.

Above.  Normal ultrasound orientation for situs solitus.

Right Hand Rule of Thumb:  Introduction

In their article “Sonographic definition of the fetal situs,” Bronshtein, Gover, and Zimmer [ 1 ]  describe a “right hand rule of thumb” to define fetal situs during transabdominal scanning, and a “left hand rule of thumb” for transvaginal scanning.

Right Hand Rule of Thumb:  Cephalic, supine, back down

Left.   The sonographer’s right hand represents the fetus with the thumb pointing to the fetal left.  The palm of the hand is anterior, or represents the ventral or face surface of the fetus.  The fetus is therefore face up, back down, and the thumb points to the fetal left.

Right.   Again, the imaginary fetus is back down with the stomach and cardiac axis pointing to the left.  (Ignore color scheme of fetal heart and vessels.)

Right Hand Rule of Thumb:  Cephalic, prone, back up

Left.   The sonographer’s right hand represents the fetus with the thumb pointing to the fetal left.  The top of the hand (dorsal surface or prone position) represents back up.

Right.  The imaginary fetus is back up with the stomach and cardiac axis pointing to the fetal left.

Right Hand Rule of Thumb:  Breech, supine, back down

Left.   The sonographer’s right hand represents the fetus with the thumb pointing to the fetal left.  The palm of the sonographer’s hand is anterior, or represents the ventral surface of the fetus.  The fetus is therefore face up, back down, and the thumb points to the fetal left.

Right .  The imaginary fetus is back down with the stomach and cardiac axis pointing to the left.  (Ignore color scheme of fetal heart and vessels).

Right Hand Rule of Thumb:  Breech, prone, back up

Right .  The imaginary fetus is back up with the stomach and cardiac axis pointing to the fetal left side.

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PSFHS: Intrapartum ultrasound image dataset for AI-based segmentation of pubic symphysis and fetal head

• Gaowen Chen   ORCID: orcid.org/0000-0003-0714-7155 1   na1 ,
• Jieyun Bai   ORCID: orcid.org/0000-0002-2847-350X 2 , 3   na1 ,
• Zhanhong Ou 2 ,
• Yaosheng Lu 2 &
• Huijin Wang 2  

Scientific Data volume  11 , Article number:  436 ( 2024 ) Cite this article

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• Medical imaging
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During the process of labor, the intrapartum transperineal ultrasound examination serves as a valuable tool, allowing direct observation of the relative positional relationship between the pubic symphysis and fetal head (PSFH). Accurate assessment of fetal head descent and the prediction of the most suitable mode of delivery heavily rely on this relationship. However, achieving an objective and quantitative interpretation of the ultrasound images necessitates precise PSFH segmentation (PSFHS), a task that is both time-consuming and demanding. Integrating the potential of artificial intelligence (AI) in the field of medical ultrasound image segmentation, the development and evaluation of AI-based models rely significantly on access to comprehensive and meticulously annotated datasets. Unfortunately, publicly accessible datasets tailored for PSFHS are notably scarce. Bridging this critical gap, we introduce a PSFHS dataset comprising 1358 images, meticulously annotated at the pixel level. The annotation process adhered to standardized protocols and involved collaboration among medical experts. Remarkably, this dataset stands as the most expansive and comprehensive resource for PSFHS to date.

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Background & summary.

Detecting maternities at risk of requiring a cesarean section is paramount in enhancing perinatal outcomes and maternal satisfaction during childbirth. Prolonged labor or failure to progress is one of the common indications that causes approximately one-third of all cesarean deliveries, underscoring the vital need for precise prediction of prolonged labor to mitigate the occurrence of unplanned emergency cesarean procedures. Notably, the prevalence of cesarean section rates has witnessed a recent increase, often attributed to indications concerning the position of the fetal head (FH) and the progression of labor 1 .

Traditional methods involving subjective digital vaginal examinations for ascertaining FH position, rotation, and descent during delivery have demonstrated a lack of accuracy at times 2 . In this context, intrapartum transperineal ultrasound has emerged as an efficacious approach for monitoring FH descent. A critical advancement offered by this technique is the angle of progress (AOP), which serves as an objective, accurate, and reproducible indicator. Notably surpassing the limitations of digital vaginal examination 3 , the AOP offers insight into the relationship between the pubic symphysis (PS) and FH (PSFH). According to the practice guideline of the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG), AOP is measured on a static 2D ultrasound image and is defined as the angle the angle between the long axis of the pubic bone and a line from the lowest edge of the pubic symphysis that tangentially touches the deepest bony part of the fetal skull. Research indicates that an AoP greater than or equal to 120 degrees is closely linked with a high chance of spontaneous vaginal delivery. Therefore, Therefore, AoP measured based on a single ultrasound image can be used as a predictive indicator of the mode of delivery.

The first step in interpreting the morphometrics is performing PSFH segmentation (PSFHS) - extracting visible PSFH contours from transperineal ultrasound images. However, PSFHS is a challenging task, involving accurate identification and delineation of the PSFH boundaries. FHs can vary widely in shape and orientation during different stages of labor, and surrounding structures like amniotic fluid and placenta can overlap with or obstruct parts of the head, introducing segmentation ambiguity. Additionally, the size and position of PSFH can vary significantly among individuals, making it difficult to develop a single generalized segmentation model. The inherent characteristics of ultrasound images, such as poor resolution, noise, and artifacts, further complicate the PSFHS process, especially during the dynamic changes in relative positions of PS and FH during the second stage of labor.

To address these challenges, automatic segmentation with Artificial Intelligence (AI) offers a promising approach 4 . Modifications to UNet structures have been introduced, incorporating attention mechanisms for improved detail capture 5 , 6 . Notably, Bai et al . devised a dual decoder strategy integrating traditional and deformable convolutions to concurrently extract morphological and global features 7 , 8 . Beyond architectural enhancements, Lu et al . explored the use of a shape-constrained loss function, reinforcing the UNet variant’s resilience to noise through the integration of a convex shape prior 9 . Despite the commendable performance of these UNet variations on proprietary datasets, their comparative evaluation remains challenging due to dataset diversity and size constraints. For example, Lu et al . released the JNU-IFM dataset 10 . Images of the JNU-IFM were acquired with the ObEye system from 51 pregnant women and collected from NanFang Hospital of Southern Medical University 10 . However, the development of AI models relies heavily on datasets from multiple centers, involving different patients, and sourced from various ultrasound devices. These factors significantly enhance the model’s performance, generalizability, and practical applicability in real-world clinical settings. Here are the key reasons why such diverse datasets are important: (1) Different centers may have patient populations with varying demographics, disease prevalence, and comorbidities; (2) Ultrasound devices from different manufacturers or even different models from the same manufacturer can produce images with varying qualities, resolutions, and characteristics; (3) Different centers might have varying protocols for image acquisition, patient preparation, and even image annotation standards; and (4) Images from different sources can have various types of noise, artifacts, or quality issues. A model trained on a diverse dataset is likely to generalize better to unseen data, reducing the risk of overfitting to specific characteristics of the training data. This is crucial for medical applications where the cost of errors can be very high. Therefore, larger and more comprehensive datasets are essential 8 .

To address these challenges and accelerate progress in AI research, it is imperative to promote data sharing and establish more comprehensive and representative datasets. In line with this objective, a proposed PSFHS dataset has been introduced, encompassing intrapartum transperineal ultrasound images that have been meticulously annotated at the pixel level through standard crowdsourcing among medical professionals. 1358 images from 1124 patients were gathered to form the PSFHS dataset. The accuracy of the pixelwise annotation, carried out by a group of trained students, was verified by expert physicians. This dataset is expected to facilitate the monitoring of labor progression through computer-aided systems and promote the practical implementation of technology in clinical settings, ultimately contributing to enhanced childbirth outcomes and improved care for both mother and fetus.

Subject characteristics

This retrospective image collection included 1124 pregnant women from two different medical institutions. Inclusion criterias were defined as: singleton pregnancy at term gestation (37 weeks or more), fetus in cephalic presentation, absence of documented fetal malformations. There are two parts in the PSFHS dataset: 1045 images from 1040 patients of Zhujiang Hospital of Southern Medical University, 313 images from 84 pregnant women from the Department of Obstetrics and Gynecology of the First Affiliated Hospital of Jinan University (Fig.  1a ). This study received approval from the institutional review boards of Zhujiang Hospital of Southern Medical University (No. 2023-SYJS-023) and the First Affiliated hospital of Jinan University (No. JNUKY-2022-019). Informed consent was waived because of the retrospective nature of the study and the analysis used anonymous medical image data.

Workflow of the establishment of the proposed dataset. ( a ) 1358 images from 1124 pregnant women were collected. ( b ) The annotation team was made up of 2 physicians and 18 annotators. (c) For each ultrasound image, two annotators conducted initial annotation. These segmentations were merged and then adjusted by a physician to obtain the ground truth. ( d ) Based on the final ground truth of PSFH, AOP measurement consisted of ellipse fitting, line identification, and AOP calculation.

Image acquisition

Ultrasound acquisitions were performed using a portable machine equipped with a 3.5 MHz probe. The ‘ObEye’ system (Guangzhou, China; http://lian-med.com ) and the Esaote My Lab were used in the First Affiliated Hospital of Jinan University and Zhujiang Hospital of Southern Medical University, respectively. During each acquisition, the operator positioned the probe longitudinally in the translabial area to visualize both the PS horizontally in the upper central part of the image and the edges of the FH in the lower part 11 . These original images were cropped to remove sensitive information about patients.

Image annotation

The team responsible for annotations included 2 proficient physicians and 18 students specializing in biomedical studies (refer to Fig.  1b ). Before commencing their tasks, annotators received comprehensive training that involved familiarizing them with the structures of PSFH and the key aspects of ultrasound images. This training was facilitated through a combination of online sessions and in-person guidance by the physicians. Each annotator was assigned 15 test images, which were subsequently assessed by the physicians. If the annotations were deemed inadequate, the images were returned to the respective student for refinement. Annotators were instructed to utilize the pencil tool in Pair ( https://www.aipair.com.cn/ ) for precise pixel-wise segmentation. They used red color for the pixel outlines of PS and green for the contour pixels of FH. In instances where the contours appeared fragmented or discontinuous, annotators were instructed to ensure that the contours maintained a complete elliptical shape. This instruction was essential considering the ultimate clinical application’s requirement to calculate AOP based on the segmented PSFH contours. The final segmentation ground truth was represented by a three-color image, where red pixels denoted PS, green pixels represented FH, and black pixels indicated the background. During the official annotation phase, each image was annotated by two annotators. Any overlapping pixels annotated by both annotators were further reviewed and adjusted by a highly experienced physician with a decade of expertise (refer to Fig.  1c ). Note: Dropped artifacts in ultrasound images can significantly impact the quality and accuracy of the images, leading to potential errors in annotation. If artifact annotation may help to develop application-oriented robust algorithms, such as uncertain segmentation algorithms.

Morphological parameters

Class imbalance is a common issue in image segmentation tasks that significantly affects the performance of deep learning models. When there is a class imbalance, it means that the number of pixels belonging to one class significantly outnumbers the pixels belonging to other classes. The pixel ratio of background to target (or among various targets) is a critical metric for understanding class imbalance. In the PSFHS dataset, the pixel proportions of PS, FH and background are, 1.78% ± 0.66%, 14.55 ± 5.73%, and 83.66 ± 6.27%, respectively. Based on the ground truth of PSFH, ellipse fitting is performed and thereby AOP is measured according to its definition—the angle between the longitudinal axis of the pubic symphysis and a line originating from its inferior edge to the leading edge of the fetal cranium tangentially (Fig.  1d ) 7 , 9 . AOP is a predictor of the mode of delivery and the average value of AOP in the PSFHS dataset is 98.33° ± 21.11°.

Data Records

All data records 12 are available as files on the web page https://doi.org/10.5281/zenodo.10969427 . The unzipped file folder of this dataset contains the original transperineal ultrasound images and annotation ground truth images. The unzipped file is organized into 2 folders, named “image_mha” and “label_mha”, that contain original transperineal ultrasound images and corresponding ground truth images, respectively. The images in these 2 folders are stored, named and arranged according to the same rule, where a specific image in the “label_mha” folder is the ground truth of the image with the same name in the “image_mha” folder. Images are named as “n.mha”, where “n” means the number of images. In the dataset, there are 1358 images (“n” from 03744 to 05101) of 1124 pregnant women. The images in the “image_mha” folder contain pixels labelled as 0, 1, or 2, where 0 represents the background, 1 represents the PS, and 2 represents the FH. These data can be accessed using the software “Insight Segmentation and Registration Toolkit”, available at https://itk.org/ .

Technical Validation

In this research, each ultrasound image underwent double annotation, followed by refinement by a medical professional. This process prompted the investigation of three distinct types of consistencies: intra-annotator consistency, referring to the same annotator at different time points; inter-annotator consistency among annotators at the same level; and inter-annotator consistency among annotators at different levels 13 .

To assess the intra-annotator consistency of the different annotators across various instances, a set of 40 images was selected from the complete dataset. These 40 images were annotated twice by three different annotators, including one physician and two others, on separate occasions. The Dice coefficient was then calculated between the annotations from the first and second rounds. The mean Dice coefficient for all 40 images and three annotators was 0.8817, with a confidence interval of 0.8502–0.9002.

To evaluate the inter-annotator consistency among annotators at the same level, discrepancies were assessed by computing the Dice coefficient between the annotations produced by the two annotators. The resulting mean Dice coefficient was 0.8750 (0.8520–0.8886).

Additionally, for the inter-annotator consistency among annotators at different levels, emphasis was placed on the first annotations. The Dice coefficient was used to measure the concordance between the physician’s mask and the annotations from the two annotators. The mean Dice coefficient for this scenario was determined to be 0.8720 (0.8520–0.8904).

Furthermore, to examine the intra-annotator consistency of the same annotator at different time points, the Dice coefficient was calculated between the first and second annotations. The resulting mean Dice coefficients were 0.8953 for the physician, 0.8811 for annotator 1, and 0.8689 for annotator 2.

Upon thorough analysis of both the original annotations and the illustrative set, it was concluded that the annotations demonstrated stability and consistency not only within a single annotator over different instances but also across various annotators. These findings collectively provide a strong basis for accurate annotation and reproducible PSFHS, as detailed in Table  1 .

Usage Notes

The whole dataset used for the PSFHS challenge of MICCAI2023 ( https://ps-fh-aop-2023.grand-challenge.org/ ) includes two parts 12 , 14 , 15 : one is this PSFHS dataset ( https://doi.org/10.5281/zenodo.10969427 ) 12 and another is from the JNU-IFM dataset ( https://doi.org/10.6084/m9.figshare.14371652 ) 16 . These images in the PSFHS dataset can also be used for the Intrapartum Ultrasound Grand Challenge (IUGC) 2024 of MICCAI 2024 ( https://codalab.lisn.upsaclay.fr/competitions/18413 ).

Code availability

No novel code was used in the construction of the PSFHS dataset.

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Acknowledgements

The work is funded by the Natural Science Foundation of Guangdong Province (2024A1515011886 and 2023A1515012833), Guangzhou Municipal Science and Technology Bureau Guangzhou Key Research and Development Program (2024B03J1283 and 2024B03J1289), the Guangdong Health Technology Promotion Project (2022 NO.132), the Science and Technology Program of Guangzhou (202201010544) and the China Scholarship Council. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We would thank these doctors and students for their contributions in data annotation (Minghong Zhou, Chao Yuan, Mengqiang Zhou, Xiaosong Jiang, Dengjiang Zhi, Ruiyu Qiu, Di Qiu, Zhanhang Song, Shen Yu, Hao Yi, Hao Liu, Jingbo Rong, Xiaoyan Xie and Jianguo Qi).

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These authors contributed equally: Gaowen Chen, Jieyun Bai.

Authors and Affiliations

Obstetrics and Gynecology Center, Zhujiang Hospital, Southern Medical University, Guangzhou, China

Gaowen Chen

Department of Electronic Engineering, College of Information Science and Technology, Jinan University, Guangzhou, China

Jieyun Bai, Zhanhong Ou, Yaosheng Lu & Huijin Wang

Auckland Bioengineering Institute, the University of Auckland, Auckland, New Zealand

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Contributions

Gaowen Chen: Project administration, Conducting intrapartum ultrasound, Manual segmentation, Writing. Jieyun Bai: Conceptualization, Project administration, Manual segmentation, Writing, Reviewing, Visualization. Zhanhong Ou: Conceptualization, Manual segmentation, Methodology, Reviewing. Yaosheng Lu: Conceptualization, Methodology, Project administration, Methodology, Reviewing. Huijin Wang: Conceptualization, Funding acquisition, Project administration, Reviewing.

Corresponding authors

Correspondence to Jieyun Bai or Yaosheng Lu .

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Chen, G., Bai, J., Ou, Z. et al. PSFHS: Intrapartum ultrasound image dataset for AI-based segmentation of pubic symphysis and fetal head. Sci Data 11 , 436 (2024). https://doi.org/10.1038/s41597-024-03266-4

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Received : 29 October 2023

Accepted : 16 April 2024

Published : 02 May 2024

DOI : https://doi.org/10.1038/s41597-024-03266-4

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