Nifedipine versus ritodrine during external cephalic version procedure: a case control study

Objective Published series regarding interventions for facilitating external cephalic version (ECV) have concluded that parenterally administered beta-stimulant tocolytics, increased ECV success rate and reduced the number of cesarean sections. However, there were insufficient data regarding calcium channel blockers to provide good evidence regarding its efficacy. Given the paucity of literature, we aimed to compare the efficacy of nifedipine to that of ritodrine on ECV success rates. Methods This is a retrospective case control study of prospectively collected data of patients who underwent ECV between January 2012 and December 2013 at Bikur Cholim Medical Center and Hadassah-Hebrew University Medical Center in Jerusalem, Israel. Patient undergoing ECV with tocolysis by ritodrine were compared with those using nifedipine as tocolysis. Patients were matched in a one-to-one ration by parity and placental location. Results Overall, 148 women received ritodrine and 148 women received nifedipine before ECV procedure. Overall success rate was higher among the ritodrine group (82.4 vs. 63.5%, p<.001). Among nulliparous and among parous, success rate was higher in the ritodrine group (78.9 vs. 57.9 and 88.6 vs. 73.5%, p=.001, p=.04, respectively). Vaginal delivery rate was higher among the ritodrine group (86.5 vs. 68.9%, p<.001). Cesarean delivery rate was 31.1% for the nifedipine group versus 13.5% in the ritodrine group (p<.001). Number needed to treat to benefit (NNTb) 5.7 (95% confidence interval 3.7-12.1). Overall, 216 of 296 (72.9%) of ECV were successful. Ritodrine was associated with higher success rates as compared with nifedipine (56.5 vs. 32.5%, p<.001). In a multivariate analysis, ritodrine tocolytic therapy was independently associated higher ECV success rates as compared to nifedipine (OR 4.54, 95% CI 2.38-9.09). Higher amniotic fluid index (OR 1.16, 95% CI 1.05-1.28) and nulliparity (OR 0.16, 95% CI 0.08-0.30) were additional independent predictors of ECV outcome. Conclusion Ritodrine significantly improve the success of ECV compared with nifedipine. Both drugs are shown to be safe.