Reproductive · Obstetrics
The facts most likely to be tested
External cephalic version (ECV) is the recommended intervention offered at 36 to 37 weeks gestation to convert a breech fetus to a cephalic presentation.
Frank breech is the most common type, characterized by flexed hips and extended knees with the feet near the fetal head.
Complete breech involves flexed hips and flexed knees, while footling breech involves one or both hips extended with a foot presenting into the cervix.
Contraindications to external cephalic version include placenta previa, prior classical cesarean section, and non-reassuring fetal status.
Planned cesarean delivery is the standard of care for persistent breech presentation at term to avoid the high risk of umbilical cord prolapse and head entrapment.
Risk factors for breech presentation include uterine anomalies, polyhydramnios, placenta previa, and fetal anomalies such as hydrocephalus.
Breech extraction is associated with significant neonatal morbidity and is generally reserved for the delivery of a second twin in a non-cephalic presentation.
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A 38-year-old G2P1 woman at 37 weeks gestation presents for a routine prenatal visit. Ultrasound confirms a singleton fetus in a frank breech position with the fetal buttocks presenting at the pelvic inlet. The patient has no history of prior uterine surgery and the placenta is located in the fundus. Fetal heart rate monitoring is reactive and amniotic fluid volume is normal. The patient desires to avoid a cesarean section if possible.
What is the most appropriate next step in management?
External cephalic version
The patient is at the appropriate gestational age (37 weeks) for an external cephalic version, and she lacks the contraindications (such as prior classical C-section or placenta previa) that would preclude the procedure.
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Etiology / Epidemiology
Occurs in 3-4% of term pregnancies. Multiparity, prematurity, and uterine anomalies are primary risk factors.
Clinical Manifestations
Fetal heart tones heard above the umbilicus. Frank breech is the most common type.
Diagnosis
Transabdominal ultrasound is the gold standard for confirmation of fetal lie.
Treatment
External cephalic version (ECV) at 36-37 weeks; contraindicated in active labor or placenta previa.
Prognosis
Increased risk of umbilical cord prolapse and birth trauma; elective cesarean section is standard for persistent breech.
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Epidemiology & Etiology
Incidence decreases as gestational age increases, with most cases resolving by 36 weeks. Major risk factors include polyhydramnios, placenta previa, and uterine leiomyomas. Fetal anomalies such as hydrocephalus or aneuploidy must be considered in persistent cases.
Pertinent Anatomy
The fetus is oriented with the buttocks or feet presenting toward the cervix. Frank breech involves flexed hips and extended knees, while complete breech involves flexion at both hips and knees.
Pathophysiology
Failure of the fetus to rotate into a cephalic position is often due to restricted intrauterine space or excessive fetal mobility. The fetus remains in a longitudinal lie but with the cephalic pole in the fundus. This orientation increases the risk of head entrapment during vaginal delivery.
Clinical Manifestations
Physical exam reveals a soft, irregular mass in the lower uterine segment rather than the hard, round fetal head. Fetal heart tones are typically auscultated above the umbilicus. Umbilical cord prolapse is a critical emergency during labor, especially with footling breech presentation.
Diagnosis
Diagnosis is suspected via Leopold maneuvers showing a soft fundal mass and a hard, ballotable head in the fundus. Transabdominal ultrasound is the gold standard to confirm fetal position and rule out placenta previa or fetal anomalies.
Treatment
External cephalic version (ECV) is offered at 36-37 weeks to rotate the fetus. Contraindications include prior classical C-section, uterine rupture risk, and non-reassuring fetal status. If ECV fails or is contraindicated, planned cesarean section is the preferred delivery method to prevent birth trauma.
Prognosis
Vaginal breech delivery carries a significantly higher risk of birth asphyxia and intracranial hemorrhage. Close monitoring for cord prolapse is mandatory if labor begins before a scheduled C-section.
Differential Diagnosis
Transverse lie: Fetal long axis is perpendicular to maternal long axis
Cephalic presentation: Normal vertex position with head down
Placenta previa: Painless third-trimester bleeding, often associated with breech
Uterine anomaly: Bicornuate uterus preventing normal fetal rotation
Fetal hydrocephalus: Head size prevents engagement in the pelvis