[Safety and efficacy of intravaginal misoprostol for cervical ripening in the third trimester of pregnancy]

Abstract

Objective: To evaluate the safety and efficacy of intravaginal misoprostol for cervical ripening in late trimester.

Method: A randomized, double-blind, placebo-controlled trial was conducted. 85 patients with indication for induction of labor and unfavorable cervices were randomly assigned to receive either intravaginal misoprostol (100 micrograms) or placebo placed in the posterior vaginal fornix at one time. The Bishop score, fetal heart rate monitoring and Doppler blood flow velocity waveforms were measured before and 12 hours after drug insertion. Placenta and decidua were observed histopathologically in some cases. Among 85 patients enrolled, 43 received misoprostol and 42 received placebo.

Results: The mean initial Bishop scores were not significantly different between the two groups, while the mean Bishop score in the misoprostol group was significantly higher than that in the placebo group (4.4 for misoprostol versus 1.0 for placebo, P < 0.01). The prevalence of spontaneous labor within 12 hours after misoprostol insertion (67.4%, 29/43) was significantly higher than that in the placebo group (14.3%, 6/42) (P < 0.01). The average Doppler velocity systolic to diastolic (S/D) ratios of umbilical artery, middle cerebral artery, renal artery were not significantly different before and 12 hours after drug insertion between both groups. There was no significant difference in frequency of abnormal fetal heart rate tracings or fetal distress and in the mean Apgar score between the two groups. Except the presence of vasodilation in villi vessels in the misoprostol group, no significant difference existed between the two groups in the placental and decidual histopathological changes.

Conclusion: Intravaginal misoprostol may be an effective and safe cervical ripening agent in late pregnancy.