Tocolysis for Repeat External Cephalic Version in Breech Presentation at Term: A Randomized, Double-Blind, Placebo-Controlled Trial

Abstract

External cephalic version (ECV) lowers the incidence of breech presentation at term and limits the need for cesarean section in noncephalic births. Although tocolytic agents may improve success rates, they are time-consuming, may cause side effects, and have not been documented to lower rates of section delivery. The investigators attempted to determine whether tocolysis is helpful when ECV is tried again after an initial failed attempt. Using a randomized, double-blind, placebo-controlled design, 124 women with breech presentation at term were enrolled in the study. All of them had undergone attempted ECV without tocolysis but had failed to respond. None of them had an abnormal cardiotocograph after the attempt and none had heart disease, diabetes, or hypertension. Participants were randomly assigned to receive either tocolysis with ritodrine or placebo during a repeat attempt at ECV. Ritodrine at a concentration of 3 mg/mL was administered by syringe pump, starting at 1 mL/hour and increasing up to a maximum of 5 mL/hour. The mother's pulse was kept below 120 beats/min. A decrease in the need for elective cesarean section for breech presentation was the major reason for a decrease in operative deliveries. The frequency of cephalic presentation at delivery was significantly increased after tocolysis (relative risk [RR], 3.21; 95% confidence interval [CI], 1.23-8.39). The incidence of cesarean section declined (RR, 0.33; 95% CI, 0.14-0.80). For multiparous women, the RR for cephalic presentation at delivery was 9.38 (95% CI, 1.64-53.62). No significant effect of tocolysis was evident in nulliparous women. There were no changes in maternal or neonatal morbidity. Although pain scores did not differ between the active treatment and placebo groups, only one woman remained totally free of pain and approximately three fourths of women experienced discomfort. A second attempt at ECV for breech presentation will be substantially more effective if tocolysis is used, and fewer cesarean sections will be necessary. Using tocolysis only after a first attempt at ECV has failed, rather than in all nulliparous women, may well produce higher overall success rates with fewer side effects.