Editor’s Note: This is the fourth installment of a six-part series that will review key concepts and articles that ob.gyns. can use to prepare for the American Board of Obstetrics and Gynecology Maintenance of Certification examination. The series is adapted from Ob/Gyn Board Master (obgynboardmaster.com), an online board review course created by Erudyte Inc. The series will cover issues in reproductive endocrinology and infertility, maternal-fetal medicine, gynecologic oncology, and female pelvic medicine, as well as general test-taking and study tips.
The American College of Obstetricians and Gynecologists’ “Practice Bulletins” are important practice management guidelines for ob.gyn. clinicians. The Practice Bulletins are rich sources of material often tested on board exams. In February 2016, ACOG issued a revised Practice Bulletin (#161) on external cephalic version outlining clinical considerations and recommendations and providing an algorithm for patient management.1 We recommend you read this bulletin and review this topic carefully.
Let’s begin with a possible medical board question: According to the Practice Bulletin, which of the following is TRUE about external cephalic version (ECV)?
A. Success rate is lower in women with a previous cesarean delivery.
B. Placental location affects the success rate.
C. External cephalic version should be stopped after 15 minutes.
D. Women at 37 weeks’ gestation are preferred candidates.
E. Tocolysis decreases success rate.
The correct answer is D.
Women at 37 weeks’ gestation are the preferred candidates for an ECV because spontaneous version would likely have already occurred by this time and the risk of spontaneous reversion is lower. Answers A-C and E are incorrect statements.
Women at 37 weeks’ gestation are the preferred candidates for an ECV.
The overall pooled success rate for ECV is 58% with a 6% pooled complication rate.
The use of parenteral tocolysis has been associated with increased success rates of ECV, though there are not enough data to make a recommendation regarding use of regional anesthesia with the procedure.
ECV is a procedure designed to turn a fetus into vertex presentation by applying external pressure to a woman’s abdomen. Women at 37 weeks’ gestation are the preferred candidates. At this gestational age, spontaneous version is most likely to have occurred, and there is decreased risk of spontaneous reversion after the ECV. All patients who are near term and found to have a fetus in a nonvertex presentation should be offered an ECV as long as there are no contraindications to the procedure. ECV is not appropriate for women who have a contraindication to a vaginal delivery.
There are limited studies of ECV in women who undergo the procedure in early labor and in those who have had a previous uterine surgery. ECV success rates are not affected by a previous cesarean delivery, though the risks of uterine rupture are not clear. The procedure should be attempted only in settings where cesarean delivery services are immediately available.
The success rates of ECV have been reported to be anywhere from 16% to 100%, with an overall pooled success of 58% with a 6% pooled complication rate. Some studies have documented higher success rates with higher parity and a transverse or oblique fetal lie. However, placental location, maternal weight, and amniotic fluid volume have not been consistently found to be predictive of ECV success. The use of parenteral tocolysis has been associated with increased success rates of ECV, though there are not enough data to make a recommendation regarding use of regional anesthesia with the procedure.
ECV should be stopped in the face of a prolonged or significant fetal bradycardia or if the patient is experiencing intolerable levels of discomfort. However, there are no guidelines to recommend the total time limit of the procedure. After the ECV, there should be fetal heart rate monitoring for at least 30 minutes and anti-D immune globulin should be administered to those women who are Rh-negative if delivery is not anticipated in the next 72 hours.
Dr. Siddighi is editor-in-chief of the Ob/Gyn Board Master and director of female pelvic medicine and reconstructive surgery and director of grand rounds at Loma Linda University Health in California. Ob.Gyn. News and Ob/Gyn Board Master are owned by the same parent company, Frontline Medical Communications.