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 ad ministered 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 ran domly assigned to receive orally administered or vaginally administered mis oprostol. Fifty micrograms of oral misoprostol or 25 mu g of vaginal misopr ostol was given every 4 hours. If cervical ripening (Bishop score of greate r than or equal to 8 or cervical dilatation of greater than or equal to 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 mi soprostol and 110 received vaginally administered misoprostol. Fewer subjec ts who received the oral preparation (34/110, 30.9%) were delivered vaginal ly within 24 hours of initiation of induction, in comparison with those who received the vaginal preparation (52/110, 47.3%) (P=.01). The average inte rval 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-tra nsformed data). Orally treated patients required significantly more doses t han 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 s ubjects and in 65 (59.1%) of 110 vaginally treated subjects (P=.01, relativ e 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 s ubjects (P=.08, relative risk 1.12, 95% confidence interval 0.99-1.27), wit h the remainder undergoing cesarean delivery. There was no difference in th e incidence of uterine contractile abnormalities (tachysystole, hypertonus, or hyperstimulation), intrapartum complications, or neonatal outcomes betw een the 2 groups. CONCLUSIONS: Oral administration of 50-mu g doses of misoprostol appears le ss effective than vaginal administration of 25-mu g doses of misoprostol fo r cervical ripening and labor induction. Further investigation is needed to determine whether orally administered misoprostol should be used for cervi cal ripening and labor induction.