Successful external cephalic version does not confer a measurable increased risk of intrapartum cesarean section in modern obstetric practice

Abstract

External cephalic version (ECV) is well established as an option for women with breech presentation at term 1. Safety of ECV is particularly important when the main alternate management of breech presentation at term is elective cesarean section (CS) 2. In an era of safe elective surgery and anesthesia, small family size and low patient and clinician tolerance of fetal risk 3, the possibility that a “successful” ECV could replace a relatively safe elective CS with a more hazardous emergency CS is of concern. The 2006 Royal College of Obstetricians and Gynaecologists' Green Top Guideline 1 quoted a doubling of emergency CS, but relied on studies published before 2003. More recent studies did not describe increased emergency CS after ECV 4, 5. We asked the question of whether women undergoing successful ECV at our Australian tertiary women's hospital in Australia were exposed to an increased intrapartum CS rate compared with women laboring with fetuses in cephalic presentation without manipulative attempts, noting that the sample size required to demonstrate a doubling of intrapartum CS rate (1) from 14% (background) to 28% is 58. Of 210 ECV attempts between January 2007 and July 2010, 119 were initially successful [56.7%, 95% confidence interval (CI): 49.9–63.2%] and 106 women (50.5%, 95% CI: 43.8–57.2%) subsequently commenced labor with a cephalically presenting fetus. The intrapartum CS rate was 15/106 (14.2%, 95% CI: 8.8–22.0%) for this group. A comparison group of 16 631 women with a singleton cephalic fetus of ≥36+0 weeks' gestation commenced labor without previous manipulation: 2328 women in this group underwent intrapartum CS (14.0%), not statistically different from women in labor after a successful ECV (Pearson′s = 0.0138, two-sided p = 0.907). Our study therefore accords with two other recent Australasian audits 4, 5 showing no increased rate of intrapartum CS after successful ECV with contemporary fetal risk management during both ECV and intrapartum.care. All three Australasian studies found CS rates following successful ECV to be within 0.5 percentage points of the CS rate in the study hospitals of the same era. Our study adds to other studies 4, 5, providing a pooled sample size of 407successful ECV candidates who subsequently labored, a pooled sample size with 80% power to detect a 5% increase or decrease around a typical background intrapartum CS rate of 14% (p < 0.05). We are confident that ECV is efficacious in promoting vaginal birth without increasing the risk of CS in labor and recommend revision of clinical guidelines to reflect modern obstetric practice of ECV and intrapartum care. We also recognize that larger sample sizes than that provided by single institution studies give more statistically precise risk estimates and encourage future collaborative research and audit.