Factors Associated With the Success of External Cephalic Version for Breech Presentation: A Retrospective Study.

Objective The aim of this study is to retrospectively evaluate additional factors potentially associated with the success of external cephalic version (ECV), including fetal buttock engagement in the maternal pelvis and umbilical cord entanglement, in addition to multiparity, th absence of maternal obesity, a posterior placental location, an estimated fetal body weight > 2500 g, adequate amniotic fluid, and the use of tocolytic agents or anesthesia. Methods This retrospective study included women with singleton pregnancies who underwent ECV at our institution between January 2011 and December 2024. Women with an abnormal placental location, fetal growth restriction, prior cesarean delivery, or missing data were excluded. Maternal background and ultrasound findings, such as maternal age, parity, body mass index, gestational age at ECV, presence of uterine contractions, use of tocolytic agents, estimated fetal body weight, fetal buttock engagement (the presence of an amniotic fluid pocket between the fetal buttocks and the internal cervical os), maximum vertical pocket, placental location, and a nuchal cord, were reviewed. A logistic regression analysis was performed to identify independent predictors of the success of ECV. Results Among 69 women who had ECV, 59 were included in the analysis after excluding those with missing data. The ECV success rate was 57.6%. Multiparity (odds ratio (OR): 1.53, 95% confidence interval (CI): 0.49-4.79) and use of tocolytic agents (OR: 3.53, 95% CI: 0.46-24.4) were associated with a trend toward higher success rate of ECV. The absence of fetal buttock engagement (OR: 24.7, 95% CI: 3.61-168.7, p = 0.001) and the absence of a nuchal cord (OR: 4.75, 95% CI: 0.93-24.3, p = 0.006) were significantly associated with successful ECV. Conclusion In addition to previously known factors, the absence of fetal buttock engagement and the absence of a nuchal cord were independently associated with successful ECV. These findings may help improve pre-procedural counseling and selection of candidates for ECV.