Prostaglandin E2 gel for cervical ripening and labour induction: a multicentre placebo-controlled trial

Abstract

OBJECTIVE: To determine the effect of a single intracervical dose of prostaglandin E2 (PGE2) gel on cervical ripening and the need for subsequent labour induction with oxytocin. DESIGN: Multicentre randomized, double-blind, placebo-controlled study. SETTING: Tertiary care hospitals. PATIENTS: A total of 397 women met the inclusion criteria: gestational age of at least 36 weeks, parity of 3 or less, a Bishop score of 4 or less, intact membranes, an indication for induction, no contraindication to vaginal delivery, no history of cesarean section or major uterine surgery, no hypersensitivity to prostaglandins, no previous attempt at cervical ripening or induction, no vaginal bleeding and no fetal abnormalities. INTERVENTION: The experimental group (203 women) received a low dose (0.5 mg) of PGE2 in 2.5 mL of gel and the control group (194) 2.5 mL of a placebo gel intracervically. The observation period was 12 hours before further induction (with oxytocin) was attempted. OUTCOME MEASURES: Ripening effect of gel, need for induction with oxytocin, rate of labour induction, time from gel administration to delivery. RESULTS: Seventeen women could not be evaluated because induction was not attempted after the first 12 hours (in nine cases) or the induction attempt was delayed for 24 hours (in six); in the other two cases the gel was in place for only 2 1/2 and 4 hours respectively before cesarean section was required. The Bishop score 12 hours after the gel administration and the difference in the score from the time of admission to the end of the 12-hour observation period were significantly higher in the experimental group than in the control group (p less than 0.001). In all, 91 (46%) of the 196 patients in the experimental group went into labour within the 12-hour observation period, as compared with 21 (11%) of the 184 in the control group (p less than 0.001). When the women who required further induction were included the rate of successful induction was 85% (166 women) and 72% (132) respectively (p less than 0.004). The mean interval from the time of gel administration to delivery was smaller in the experimental group than in the control group (19.8 v. 24.1 hours respectively) (p less than 0.001). CONCLUSIONS: A single, low dose of PGE2 gel administered intracervically is a safe and reliable method of dealing with indicated but potentially difficult inductions.