Height of elevated fetal buttock for prediction of successful external cephalic version

To increase the rate of successful external cephalic version (ECV) and to minimize the complications, it is important to identify the predictors of success. Therefore, the purpose of this study was to investigate whether the height of the elevated fetal buttock (HOB) is a valuable predictor of successful ECV or not.

This prospective study was conducted from August 2016 to June 2018. A total of 139 pregnant women with breech presentation were enrolled in the study. HOB from the maternal pubic symphysis was measured on ultrasonography. The predictability and cut-off value of HOB for successful ECV were evaluated.

Among the 139 patients, 114 (82%) had successful ECV. The adjusted odds ratio for multiparity, amniotic fluid index (AFI) >14 cm, and HOB >7.8 cm were 10.80 (95% confidence interval [CI], 1.57-74.94), 5.26 (95% CI, 1.06-26.19), and 10.50 (95% CI, 1.03-107.12), respectively. Areas under the curve (AUCs) for AFI, HOB, and parity were 0.66 (95% CI, 0.54-0.78), 0.74 (95% CI, 0.64-0.85), and 0.69 (95% CI, 0.62-0.76), respectively. HOB had the largest AUC, but there were no significant differences among the AUCs of other factors. The cut-off value of HOB was 6 cm.

This study showed that the AUC of HOB was greater than that of parity and AFI, although it was not statistically significant. As HOB is a noninvasive and comprehensive marker to predict successful ECV, consideration of HOB would be helpful before conducting ECV. Further studies are needed.