Objective: To evaluate predictive variables for successful external cephalic version.
Methods: During 1987–1996, 128 women had external cephalic version attempts. Uterine tone, fetal spine position, breech location, breech type, gestational age, placental location, parity, maternal weight, amniotic fluid index, and estimated fetal weight were evaluated as predictors of success.
Results: Seventy-eight (64%) women were successfully converted from breech to vertex presentation. All subjects with low uterine tone had successful version. In women with high uterine tone, the combination of anterior or lateral fetal spine, noncornual placental location, and breech location out of the pelvis predicted success. Other independent variables associated with successful version included non-frank breech presentation, gestational age under 38 weeks, and parity of at least 1.
Conclusion: Uterine tone may be the most important predictor of success when selecting candidates for external cephalic version.
During the 1950s, interest in external version declined after reports of fetal death and maternal morbidity.1 Early procedures often involved preterm fetuses, general anesthesia, and inappropriate fetal monitoring. By the 1960s, vaginal delivery was the generally accepted approach to breech presentation. By the 1970s, studies suggested increased neonatal morbidity and birth injury with breech delivery.2 Those apprehensions in an intensified medicolegal atmosphere led to a strong trend away from the teaching and use of breech vaginal delivery. An ACOG Technical Bulletin in 1986 stated that “the controversies related to breech birth cannot be answered by a consensus statement at this time ….”3 A 1988 survey of the Society of Perinatal Obstetricians found that 14% thought there was “adequate scientific documentation demonstrating that cesarean section is the preferred mode of delivery.”4 Most members believed that multicenter randomized trials were needed to establish the optimal mode of delivery. Critics, however, suggested that such studies would be difficult. The overall result has been a dramatic increase in the cesarean rate for breech presentation.
An increasingly popular alternative to cesarean delivery has been renewed interest in external cephalic version. Unfortunately, not all women present with equal chances of a successful procedure, and improved subject selection would reduce procedure costs and increase success rates. The present study was done to assess the relative importance of ten objective variables for predicting successful external cephalic version.
Uterine tone is an important predictor of successful external cephalic version.
University of New Mexico Hospital, Presbyterian Hospital, and Perinatal Associates of New Mexico, Albuquerque, New Mexico, and Perinatal Associates of California, Sharp Memorial Hospital, San Diego, California.
Address reprint requests to: Gary A. Aisenbrey, MD, Perinatal Associates of New Mexico, 201 Cedar SE, Suite 405, Albuquerque, NM 87106
Received December 28, 1998. Received in revised form April 5, 1999. Accepted April 8, 1999.