according to results of a single-center retrospective study.
Writing in Obstetrics & Gynecology, Ofer Isakov, MD, PhD, and colleagues from the Sourasky Medical Center, Tel Aviv, reported the results of a study of 250 women with singleton pregnancies and breech presentation who underwent external cephalic version (ECV) to turn the baby at 36-41 weeks’ gestation.
The overall success rate of the procedure was 65%. However, women with no forebag – the pocket of amniotic fluid in front of the fetal presenting part – had a 3%-10% chance of successful version, while those with a forebag size greater than 1 cm had a 96%-97% probability of success.
Women with a BMI greater than 29 had a very low chance of success, which the authors suggested was likely attributable to a thicker abdominal wall that made manipulation more difficult. However, among women with a BMI of 29 or below, success was significantly associated with forebag size.
Among women with a forebag of 1 cm in size, multiparous women had a significantly higher chance of success than nulliparous women (81%-91% vs. 0%-24%, respectively).
Dr. Isakov and colleagues suggested that the impact of multiparity could relate to late engagement or the relative laxity of the abdomen in women who had experienced previous births.
The authors then developed a decision tree predictive model of success for ECV, which had a prediction accuracy of 92%.
“External version is a simple and effective procedure that can reduce the cesarean delivery rate, but counseling patients on the risks and success rates of version is challenging owing to the lack of validated models to predict success,” Dr. Isakov and colleagues wrote. “The ability to predict the outcome of an ECV attempt may improve the rates of patient consent and prevent the performance of many unpleasant procedures with low chance for success.”
They noted that their success rate was higher than that seen in other studies of ECV and suggested this may be because all the procedures were performed by a single experienced practitioner, and the mean BMI of the cohort was lower than that in earlier studies.
None of the authors declared any relevant financial disclosures, and there was no external funding.
SOURCE: Isakov O et al. Obstet Gynecol. 2019;133:869-78.