Extra-amniotic saline, laminaria, or prostaglandin E-2 gel for labor induction with unfavorable cervix: A randomized controlled trial

Objective: To determine which of three methods of cervical ripening resulte d in the lowest cesarean rate in women with unfavorable cervices and indica tions for labor induction. Methods: Consenting women with singleton gestations, vertex presentations, and unfavorable cervices (dilatation under 2 cm and effacement under 75%) w ere randomly assigned to laminaria and standard intravenous oxytocin, seria l doses of intracervical prostoglandin (PG) E-2 gel (Prepidil, Pharmacia & Upjohn, Inc., Kalamazoo, MI) 0.5 mu g every 6 hours for two doses followed by oxytocin if indicated, or extra-amniotic saline infusion and oxytocin. Results: An interim analysis after recruitment of 321 subjects, 67% of the planned sample, found similar cesarean rates for the three groups (laminari a 36%; PGE(2) gel 33%; saline infusion 29%; P = .59); however, the mean ran domization-to-delivery interval was significantly longer in the PGE(2) grou p. Stochastic curtailment, as part of the interim analysis, indicated a low likelihood of achieving a statistically significant difference in cesarean rates between PGE(2) gel and the other two groups. Therefore, we completed the study with saline infusion and laminaria. The saline infusion and Lami naria groups had similar preinduction characteristics. The cesarean rates w ere similar (saline infusion 25.4% versus laminaria 30.3%; P = .32), but th e mean interval from randomization to delivery was shorter in the saline in fusion group (18.0 versus 21.5 hours, P = .002). There were no significant differences in selected maternal and neonatal morbidities. Conclusion: Cervical ripening with extra-amniotic saline infusion, PGE(2), or laminaria resulted in comparable cesarean rates in women with an unfavor able cervix and indications for labor induction. Extra-amniotic saline infu sion had the shortest randomization-to-delivery interval without increasing maternal or neonatal morbidity. (Obstet Gynecol 2000;96:106-12. (C) 2000 b y The American College of Obstetricians and Gynecologists.).