A Randomized Comparison of Transcervical Foley Bulb With Vaginal Misoprostol to Vaginal Misoprostol Alone for Induction of Labor

1. Objectives The hypothesis is that cervical ripening using a foley bulb together with vaginal misoprostol (cytotec) will result in shorter induction to delivery time compared with vaginal misoprostol alone
2. Background The rate of induction of labor in the United States is approximately 20% of all births. Induction of labor can result in prolonged labor and increases the rate of cesarean delivery, both of which are associated with increased maternal and neonatal morbidity. Ripening of an unfavorable cervix has become an integral part of the labor induction process. The best method of cervical ripening remains controversial; no one method has proved to be superior. Women requiring labor induction often present with unfavorable cervices which can lead to a prolonged induction. Cervical ripening is often done to increase the likelihood of successful labor induction.

Misoprostol (cytotec) is PGE1 analog and widely used for cervical ripening and is the preferred method of induction of labor based on the safety reported literature. Low-dose (25 mcg) intravaginal misoprostol appears to be safe and effective for cervical ripening in term pregnancy for patients without a history of cesarean section. Compared with other cervical ripening methods, misoprostol has an increased rate of vaginal delivery within 24 hours without significant differences in cesarean section rates or fetal outcomes.

The use of the foley catheter for induction of labor was first described by Krause in 1953. In 1967 Embrey and Mollison reported a 94% successful induction rate after using the foley catheter for cervical ripening. Since then, several studies found transcervical foley catheters as effective as prostaglandins preparations for ripening without an increased risk of uterine rupture.

There are many proposed methods for induction of labor including mechanical (transcervical foley bulb) and chemical methods (prostaglandins, oxytocin). A number of randomized trials have compared the use of foley bulb, oxytocin and misoprostol in different combinations for induction of labor and their results are contradictory with regards to induction to delivery time, successful vaginal delivery and labor complications.

There are two studies that evaluated the foley bulb with misoprostol comparing to misoprostol alone. Carbone el al study, found the mean induction to delivery time was 3 hours shorter with the combination of the foley bulb and vaginal misoprostol when compared to vaginal misoprostol alone. In a study by Chung et al, there was no difference in the induction to delivery time.