Extraamniotic saline infusion is promising in preparing the cervix for induction of labor

The application of local prostaglandins before induction of labor in women with an unripe cervix is standard procedure in Sweden. Side effects include uterine hypertonus and occasionally fetal heart rate abnormalities. Failed ripening is reported in up to 25% of cases. A previous report of ripening of the cervix by use of extraamniotic physiologic saline infusion through a Foley catheter applied in the cervix claimed results superior to topical prostaglandins.

To conduct a prospective randomized trial of extraamniotic saline infusion and intracervical application of dinoprost 0.5 mg on cervical ripening and outcome of labor.

Eighty-five term singleton pregnant women with unripe cervices where induction of labor was indicated were randomized to prostaglandin or saline infusion after obtaining informed consent. Outcome variables were improvement of cervical score, induction delivery time and mode of delivery.

The 42 women in the saline infusion group obtained significantly (p < or = 0.001) higher cervical scores and shorter induction delivery intervals (p < or = 0.005) than the 43 women in the prostaglandin group. Cases of unripe cervix after 24 hours were significantly (p < or = 0.01) fewer in the saline group. There were more Cesarean sections in the saline group, but this difference was not significant. Saline infusion did not induce uterine activity and oxytocin was given in every case after the expulsion of the catheter.

In this study extraamniotic saline infusion was a more efficacious method for ripening of the cervix than intracervical prostaglandin. The absence of early painful contractions is an advantage, but effective stimulation of labor is required to effect delivery after maturation of the cervix.