External cephalic version (ECV) is often recommended to avoid a cesarean delivery (CD) in women with a fetus in the breech position. International guidelines recommend that all women with an uncomplicated breech pregnancy at term should be offered an ECV. These guidelines also list contraindications to ECV; however, excluding patients from ECV in the presence of only 1 clinical factor that could affect its success rate is undesirable. This systematic review was performed to determine whether the contraindications to ECV in guidelines are consistent and based on empirical data and to offer recommendations for ECV contraindications.
Guidelines and databases were identified and searched for studies reporting on ECV and citing contraindications. All studies reporting on ECV in a singleton pregnancy from 36 weeks without a contraindication for vaginal delivery were selected. Contraindications were categorized as maternal, fetal, and other factors.
The electronic search for guidelines found 5 sets that reported on 18 contraindications, with 5 to 13 contraindications per guideline. The literature search provided 890 studies on ECV; of 261 retrieved, 60 articles were assessed and reported on 39 different contraindications to ECV. Forty-three studies were cohort studies, 6 were case-control studies, and 11 were randomized controlled trials. The 39 contraindications were separated into 3 categories. Maternal factors included uterine anomaly, preeclampsia/hypertension, ruptured membranes, antepartum or second-trimester bleeding, abruptio placentae in history, active labor, cardiac disease, obesity, electrocardiogram abnormalities, abnormal pelvis, age older than 45 years, allergies, CD in history, diabetes, dilated cervix, grand multipara, hyperthyroidism, and irregular T4. The fetal factors were growth restriction, abnormal cardiotocography, fetal anomaly, macrosomia, hyperextension of head, unstable lie, Doppler abnormalities, fetal distress, positive nonstress test, Rhesus immunization, and uteroplacental transfusion. Other factors included oligohydramnios, restrictive nuchal cord, inexperienced obstetrician, anterior placenta, polyhydramnios, and single umbilical artery.
For each contraindication, the literature was searched to determine whether it was an evidence-based contraindication. Studies reporting on breech presentation in a woman with a previous CD or with premature rupture of the membranes indicated that an ECV attempt was possible and could be successful. Evidence was not found for other maternal factors as contraindications, and the present authors concluded that the main risk factors are based on clinical physiologic knowledge. No studies reported on the relationship between ECV and placental abruption, but it is a rare complication of ECV. Considering the seriousness of the complication and the higher risk of recurrence in patients with a history of placental abruption, ECV should be withheld in patients suspected of an imminent or history of abruption.
One meta-analysis examined the relationship between the success rate of ECV and estimated fetal weight. No adverse events were reported for small-for-gestational age fetuses, but the evidence was insufficient to conclude that ECV is safe in cases of severe growth restriction with Doppler abnormalities. Three reviews reported on the relationship between success rates of ECV and oligohydramnios and concluded that an amniotic fluid index greater than 10 cm was associated with an increased chance of success, but these studies did not report any adverse events of ECV in women with a low amniotic fluid index. One review reported the relationship between anterior placenta and a lower success rate of ECV, but in none of the studies were complications reported.
Oligohydramnios was the only contraindication mentioned in all guidelines. Of the 39 contraindications to ECV mentioned in the guidelines and literature, evidence could be assessed for only 6. The adherence to contraindications that were not well defined indicates that ECV may be withheld from a high proportion of women who could benefit from the procedure without increased risks of adverse events. The authors propose 3 contraindications to ECV. Maternal contraindications are placental abruption in history or signs of this complication and severe preeclampsia or HELLP syndrome (both level III evidence); fetal factors are signs of fetal distress, that is, abnormal cardiotocography or abnormal Doppler flow or both (level III evidence). Contraindications to ECV should be limited to those with clear empirical evidence or to factors with a clear pathophysiologic relevance.
Department of Obstetrics and Gynecology, Academic Medical Centre, Amsterdam (A.N.R., A.G., F.V., B.W.J.M., M.K.), and TNO Department of Child Health, Leiden (M.R.), the Netherlands