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

## TL;DR

This study identifies new factors, like fetal buttock engagement and nuchal cord absence, that predict the success of external cephalic version for breech presentation.

## Contribution

The study identifies fetal buttock engagement and nuchal cord absence as novel predictors of ECV success.

## Key findings

- The absence of fetal buttock engagement was strongly associated with successful ECV (OR: 24.7).
- The absence of a nuchal cord was significantly linked to successful ECV (OR: 4.75).
- Multiparity and use of tocolytic agents showed a trend toward higher ECV success.

## Abstract

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.