A comparison of orally administered misoprostol with vaginally administered misoprostol for cervical ripening and labor induction.

OBJECTIVE: Our purpose was to compare orally administered with vaginally administered misoprostol for cervical ripening and labor induction.

MATERIAL AND METHODS: Two hundred twenty subjects with medical or obstetric indications for labor induction and undilated, uneffaced cervices were randomly assigned to receive orally administered or vaginally administered misoprostol. Fifty micrograms of oral misoprostol or 25 microgram of vaginal misoprostol was given every 4 hours. If cervical ripening (Bishop score of >/=8 or cervical dilatation of >/=3) or active labor did not occur, repeated doses were given to a maximum of 6 doses or 24 hours. Thereafter, oxytocin was administered intravenously by a standardized incremental infusion protocol to a maximum of 22 mU/min.

RESULTS: Of the 220 subjects evaluated, 110 received orally administered misoprostol and 110 received vaginally administered misoprostol. Fewer subjects who received the oral preparation (34/110, 30.9%) were delivered vaginally within 24 hours of initiation of induction, in comparison with those who received the vaginal preparation (52/110, 47.3%) (P =.01). The average interval from start of induction to vaginal delivery was nearly 6 hours longer in the oral treatment group (mean and SD 1737.9 +/- 845.7 minutes) than in the vaginal treatment group (mean and SD 1393.2 +/- 767.9) (P =.005, log-transformed data). Orally treated patients required significantly more doses than vaginally treated patients (orally administered doses: mean and SD 3.3 +/- 1.7; vaginally administered doses: mean and SD 2.3 +/- 1.2) (P <.0001). Oxytocin administration was necessary in 83 (75.4%) of 110 orally treated subjects and in 65 (59.1%) of 110 vaginally treated subjects (P =.01, relative risk 1. 28, 95% confidence interval 1.06-1.54). Vaginal delivery occurred in 95 (86.4%) orally treated subjects and in 85 (77.3%) vaginally treated subjects (P =.08, relative risk 1.12, 95% confidence interval 0.99-1.27), with the remainder undergoing cesarean delivery. There was no difference in the incidence of uterine contractile abnormalities (tachysystole, hypertonus, or hyperstimulation), intrapartum complications, or neonatal outcomes between the 2 groups.

CONCLUSIONS: Oral administration of 50-microgram doses of misoprostol appears less effective than vaginal administration of 25-microgram doses of misoprostol for cervical ripening and labor induction. Further investigation is needed to determine whether orally administered misoprostol should be used for cervical ripening and labor induction.