A Randomized Trial of Misoprostol and Extra-amniotic Saline Infusion for Cervical Ripening and Labor Induction

Abstract

In Brief Objective To compare the cesarean rates in women undergoing induction of labor with unfavorable cervices who receive either misoprostol or extra-amniotic saline infusion. Methods We assigned 250 women undergoing indicated induction of labor randomly to misoprostol (50 μg every 4 hours for three doses with or without oxytocin) or extra-amniotic saline infusion and oxytocin. Each eligible subject had a singleton gestation, vertex presentation, intact membranes, cervical dilation no more than 2 cm, and effacement no more than 50%. Results Two hundred forty-eight women were studied after two exclusions; 120 were assigned to misoprostol, and 128 to extra-amniotic saline infusion. This sample size ensured an 80% chance of detecting an intergroup difference in cesarean rates of at least two-fold. The groups were similar in age, race, parity, indication for induction, and gestational age. The extra-amniotic saline infusion group had a significantly lower median initial dilation; however, at 12 hours, this group was significantly more dilated. The groups also were similar in epidural use, chorioamnionitis rates, endometritis rates, birth weights, and neonatal outcomes. Overall, 23% of women underwent cesarean deliveries, 18% and 27% for the misoprostol and extra-amniotic saline infusion groups, respectively (P = .12). There were no significant differences in the median time to either vaginal or cesarean delivery between the two groups. Eighty-one percent of women were delivered in less than 24 hours from initiation of induction; 78% in the misoprostol group, and 84% in the extra-amniotic saline infusion group (P = .19). Conclusion Both methods of labor induction appear to be equally effective in this group of women at high risk for cesarean delivery and prolonged induction of labor. Misoprostol and extra-amniotic saline infusion appear to be equally effective for cervical ripening and labor induction in women with unfavorable cervices.