Employing nifedipine as a tocolytic agent prior to external cephalic version

Abstract

External cephalic version (ECV) is accepted as a means of reducing the rate of breech presentation at term. Routine use of tocolysis prior to an ECV has been described to increase its success rate. The study's objective was to evaluate the efficacy of oral nifedipine as a tocolytic agent prior to ECV, and to compare it with intravenous ritodrine (IR). Women with breech presentation at term considered suitable for ECV were given nifedipine prior to the procedure. The success rate was compared to a cohort of women who underwent an ECV attempt at our department during the years 1999-2002 using IR prior to the procedure. Power analysis indicated that 70 women were needed in each group to detect a difference of 25% from our baseline success rate of 50%. Seventy-six women receiving nifedipine before their ECV attempt were compared to 90 women who received IR. Age, parity, gestational age at ECV, type of breech, placental location, fetal weight, and gestational age at delivery were not different between the groups. The overall success rate was 54% and 50% in the nifedipine and ritodrine groups respectively (p=0.6). The success rate among primiparous women was 35% and 29% respectively (p=0.8). The success rate among multiparous women was 64% and 63% respectively (p=1.0). The success rate was statistically different between primiparous and multiparous women in each group (p<0.05). Oral nifedipine may be as effective as IR when administered before ECV.