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

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.