A randomized trial of extra-amniotic saline infusion versus laminaria for cervical ripening

Abstract

Objective: To compare extra-amniotic saline infusion versus laminaria for cervical ripening and labor induction.

Methods: Patients of at least 34 weeks' gestation with a Bishop score of 3 or less were randomized to either laminaria ripening for 6 hours or more followed by oxytocin induction versus initiation of extra-amniotic saline infusion at the start of oxytocin induction. Indications for induction included 41 weeks' gestation or greater, hypertensive disease, diabetes, oligohydramnios, suspect fetal growth, and nonreassuring fetal testing.

Results: There were no significant differences in maternal age, race, parity, gestational age, or indications for induction between the two groups (extra-amniotic saline infusion group, n = 26, laminaria group, n = 26). After only 3 hours of oxytocin induction, patients in the extra-amniotic saline infusion group achieved an identical distribution of Bishop scores compared with the patients in the laminaria group after 6 hours or more of pre-induction ripening as well as 3 hours of oxytocin induction. There were no differences in rates of cesarean delivery (extra-amniotic saline infusion 35%, laminaria 35%), infectious complications, or neonatal outcomes between the two groups. The induction-to-delivery interval (+/- standard deviation) was significantly shortened with extra-amniotic saline infusion (extra-amniotic saline infusion 12.9 +/- 5.7 hours versus laminaria 16.9 +/- 7.1 hours, P = .03). In addition, fewer cesarean deliveries were performed for failed inductions (cervix less than 5 cm dilated) in the extra-amniotic saline infusion group (one of 26 versus six of 26, P = .049).

Conclusion: Extra-amniotic saline infusion offers potential advantages over the use of laminaria. Extra-amniotic saline infusion saves a significant amount of time both by obviating the need for pre-induction cervical ripening and in shortening the induction-to-delivery interval. Also, fewer patients required cesarean delivery for failed induction of labor with extra-amniotic saline infusion.