A COMPARISON OF INTERMITTENT VAGINAL ADMINISTRATION OF MISOPROSTOL WITH CONTINUOUS DINOPROSTONE FOR CERVICAL RIPENING AND LABOR INDUCTION

OBJECTIVE: Our purpose was to compare the effect of vaginal administra tion of misoprostol (Cytotec) with that of dinoprostone (Cervidil) on cervical ripening and labor induction. STUDY DESIGN: Two hundred patie nts with indications for induction of labor and unfavorable cervical e xaminations were randomly assigned to receive vaginally administered m isoprostol (prostaglandin E-1) or the dinoprostone (prostaglandin E-2) vaginal insert. Twenty-five microgram tablets of misoprostol were pla ced in the posterior vaginal fornix every 4 hours for a maximum of six doses. Additional misoprostol was not given after either spontaneous rupture of membranes, adequate cervical ripening (Bishop score of grea ter than or equal to 8 or cervical dilatation of greater than or equal to 3 cm), or beginning of active labor. The vaginal insert, Cervidil, containing 10 mg of dinoprostone in a timed-release preparation was p laced in the posterior vaginal fornix for a maximum period of 24 hours . The vaginal insert was removed for spontaneous rupture of membranes, entry into active labor, adequate cervical ripening, or abnormality o f uterine contractile pattern or fetal cardiac activity. RESULTS: Of t he 200 patients enrolled, 99 were randomized to misoprostol and 101 to dinoprostone. The average interval from start of induction to vaginal delivery was 1 hour shorter in the misoprostol group (1296.7 +/- 722. 1 minutes) than in the dinoprostone group (1360.0 +/- 792.0 minutes), but this difference was not statistically significant (p = 0.97). Oxyt ocin augmentation of labor was used in 50 (50.5%) misoprostol-treated patients and 43 (43.5%) dinoprostone-treated patients (relative risk 1 .14, 95% confidence interval 0.86 to 1.51, p = 0.35). There were no si gnificant differences between routes of delivery with misoprostol or d inoprostone. Overall, 38 patients (19.3%) had cesarean deliveries. The re was a significantly lower prevalence of tachysystole (six or more u terine contractions in a 10-minute window for two consecutive 10-minut e periods) in the misoprostol group (7.1%) than in the dinoprostone gr oup (18.4%) (relative risk 0.52, 95% confidence interval 0.31 to 0.89, p = 0.02). There were no significant differences in frequency of uter ine hyperstimulation or hypertonus. Abnormal fetal heart rate tracings were found in 23 (23.2%) of misoprostol-treated patients and 35 (35.7 %) of dinoprostone-treated patients (relative risk 0.73, 95% confidenc e interval 0.52 to 1.01, p = 0.0546). No significant differences were found in meconium passage, 1- or 5-minute Apgar scores <7, neonatal re suscitations, or admissions to the neonatal intensive care unit betwee n the two groups. CONCLUSIONS: Vaginally administered misoprostol is a s effective as dinoprostone for cervical ripening and the induction of labor. Mean time intervals to delivery, need for oxytocin augmentatio n, and routes of delivery were similar between the two groups. Inciden ce of uterine tachysystole with misoprostol every 4 hours was signific antly less than with dinoprostone.