Objective: To compare the efficacy, side effects, and complications of high-dose vaginal misoprostol with concentrated intravenous oxytocin plus low-dose vaginal prostaglandin (PGE(2)) for second-trimester labor induction.
Methods: One hundred twenty-six consenting women with maternal or fetal indications for pregnancy termination and no prior cesarean delivery were randomly assigned to receive either vaginal misoprostol 600 microg 1x, 400 microg every 4 hours 5x (misoprostol group, n = 60) or escalating-dose concentrated oxytocin infusions (277-1,667 mU/min) plus vaginal PGE(2) 10 mg every 6 hours 4x (oxytocin group, n = 66). Both groups received concurrent extra-amniotic saline infusion for cervical ripening. Women who failed their assigned regimen received 20 mg of PGE(2) suppositories every 4 hours until delivery. Analysis was by intent to treat.
Results: Demographic characteristics were similar between study groups. Median induction-to-delivery interval was significantly shorter in the misoprostol group (12 hours) than in the oxytocin group (17 hours; P <.001). There was a higher induction success rate at 24 hours in the misoprostol group (95%) than in the oxytocin group (85%; P =.06), although this difference did not reach statistical significance. The incidence of live birth (25% versus 17%), chorioamnionitis (5% versus 2%), and postpartum hemorrhage greater than 500 mL (3% versus 3%) were similar between the misoprostol and oxytocin groups, respectively. Diarrhea (2% versus 11%; P =.04), nausea/emesis (25% versus 42%; P =.04), and retained placenta requiring curettage (2% versus 15%; P =.008) were significantly less common in the misoprostol group when compared with the oxytocin group, respectively. Isolated intrapartum fever, however, was more frequent in the misoprostol group (67%) than in the oxytocin group (21%; P <.001).
Conclusion: Compared with concentrated oxytocin plus low-dose vaginal PGE(2), high-dose vaginal misoprostol is associated with significantly shorter induction-to-delivery intervals, fewer side effects, a lower incidence of retained placenta, and comparable incidence of live birth.