Labor induction during pregnancy is sometimes necessary when the benefits of intervening are greater than the risks of continuing the pregnancy. Lack of adequate cervical ripening decreases the likelihood of a successful labor induction. Various oral and vaginal methods are available to ripen the cervix. Misoprostol (Cytotec) is a commonly used medication that is available in oral and vaginal preparations. Misoprostol for cervical ripening is an off-label use, but multiple studies have proved it to be safe and effective. However, the appropriate dosage and best route have not been established. High doses can induce more cervical changes but can increase the risk of hyperstimulation of the uterus. Colón and associates evaluated the effectiveness and safety of a stepwise dosing of oral misoprostol compared with vaginal misoprostol for cervical ripening.
The study included women at 32 to 42 weeks’ gestation who were admitted for labor induction because of obstetric or medical indications. Inclusion criteria were an unfavorable cervix (Bishop score of 6 or less), intact or ruptured membranes, cephalic presentation, and a reassuring fetal heart rate tracing. The oral misoprostol treatment group received an initial dosage of 50 mcg of misoprostol followed by 100 mcg every four hours for up to four doses. The vaginal misoprostol group received 25 mcg every four hours for up to four doses. Misoprostol was withheld if adequate uterine activity occurred (three or more contractions in 10 minutes), a Bishop score of 8 or more was reached, or active labor began. The main outcome of the study was the time from first misoprostol dose to delivery. Other outcome measures included patient satisfaction and treatment side effects.
Of the 204 women who met the inclusion criteria, 93 were assigned to the oral misoprostol group and 111 to the vaginal misoprostol group. There were no significant differences between the oral and vaginal groups with regard to the interval between the start of misoprostol and delivery (21.1 and 21.5 hours, respectively). Hyper-stimulation occurred in 2.2 percent of patients in the oral treatment group and in 5.4 percent of patients in the vaginal treatment group, but this difference was not statistically significant. Significantly more women in the vaginal treatment group underwent cesarean section compared with the oral group, but this was attributable to better tolerance of more doses among the oral treatment group. Side effects and patient satisfaction were the same for both treatment groups.
The authors conclude that the stepwise oral misoprostol regimen was as effective as the vaginal misoprostol regimen for cervical ripening. The oral regimen had a lower incidence of uterine hyperstimulation, no increase in side effects, and was associated with a lower cesarean rate and a higher rate of patient satisfaction.