Misoprostol: an effective agent for cervical ripening and labor induction

Abstract

Objective: Our purpose was to compare the safety and efficacy of intravaginal misoprostol versus intracervical prostaglandin E2 gel (dinoprostone) for preinduction cervical ripening and induction of labor.

Study design: Two hundred seventy-six patients with indications for induction of labor and unfavorable cervices were randomly assigned to receive either intravaginal misoprostol or intracervical dinoprostone. Twenty-five micrograms of misoprostol were placed in the posterior vaginal fornix every 3 hours, with a potential maximum of eight doses. Prostaglandin E2 in gel form, 0.5 mg, was placed in the endocervix every 6 hours, with a maximum of three doses. Further medication was withheld with the occurrence of spontaneous rupture of membranes, entry into active phase of labor, or a "prolonged contraction response."

Results: Among those evaluated, 138 received misoprostol and 137 received dinoprostone. The average interval from start of induction to vaginal delivery was shorter in the misoprostol group (1323.0 +/- 844.4 minutes) than in the dinoprostone group (1532.4 +/- 706.5 minutes) (p < 0.05). Need for oxytocin augmentation of labor occurred more commonly in the dinoprostone group (72.6%) than in the misoprostol group (45.7%) (p < 0.0001). There were no significant differences in the routes of delivery. Twenty-eight of the misoprostol-treated patients (20.3%) and thirty-eight of the dinoprostone-treated patients (27.7%) required abdominal delivery. Complications such as uterine tachysystole and thick meconium passage occurred with similar frequency in the two treatment groups.

Conclusions: Intravaginal administration of misoprostol appears to be as effective as intracervical dinoprostone for cervical ripening and labor induction. Complications associated with prostaglandin administration were not statistically different between the two treatment groups. The cost of misoprostol ($0.36/100 micrograms) is much less than that of dinoprostone ($75/0.5 mg).

PIP: In a comparative study conducted in 1994 among 276 women presenting to a Los Angeles, California (US), hospital with indications for induction of labor but unfavorable cervices, intravaginal administration of misoprostol was as effective as intracervical prostaglandin E2 gel (dinoprostone) for cervical ripening and labor induction. 138 women were randomly assigned to receive 25 mcg of misoprostol placed in the posterior vaginal fornix every 3 hours (maximum of 8 doses), while 137 were given 0.5 mg dinoprostone placed in the endocervix every 6 hours (maximum of 3 doses). The average interval from start of induction to vaginal delivery was 1323 +or- 844.4 minutes in the misoprostol group compared with 1532 +or- 706.5 minutes in the dinoprostone group. 45.7% of women in the misoprostol group compared with 72.6% in the dinoprostone group required oxytocin augmentation of labor. The goal of vaginal delivery within 24 hours was achieved by 65.5% of women in the misoprostol group, but only by 41.4% of those in the dinoprostone group. The cesarean section rates were 20.3% and 27.7%, respectively. Complications such as uterine tachysystole and meconium passage occurred with similar frequency in both groups. These findings suggest that misoprostol is a safe, effective, and inexpensive (US$0.36 per tablet) agent for cervical ripening and labor induction.