Intravaginal isonicotinic acid hydrazide (INH) versus misoprostol for cervical ripening prior to hysteroscopy

OBJECTIVE: The aim of the present study was to compare the efficacy of vaginal isoniazid (isonicotinic acid hydrazide [INH]) and vaginal misoprostol in cervical ripening before hysteroscopic surgery. METHODS: This randomized controlled trial included patients scheduled for hysteroscopic surgery during April 2016 and June 2017. The inclusion criteria were as follows: postmenopausal women or those at premenopausal age who had not had a vaginal delivery and candidate for diagnostic or operative hysteroscopy with closed cervix before intervention. The INH group (intervention group) received 900 mg of vaginal isoniazid (three 300-mg pills) 6–8 hours before hysteroscopic surgery. The misoprostol group (control group) received 400 micrograms of vaginal misoprostol 6–8 hours before hysteroscopic surgery. Finally, the efficacy of the 2 agents was comparatively analyzed. RESULTS: Baseline characteristics were comparable between the groups. In 67 cases in the INH group (95%) and 45 in the misoprostol group (50%), hysteroscopic entry was successful without additional mechanical dilation, and this difference was statistically significant (P=0.001). The odds ratio (OR) obtained in this study was 0.57 for both INH and misoprostol groups (OR, 0.57; 95% confidence interval, 0.43–0.75). Further, 19 cases in the INH group vs. 45 cases in the misoprostol group did not respond to the intervention, indicating statistically significance (P=0.001). CONCLUSION: Vaginal INH is more effective than misoprostol in cervical ripening before hysteroscopic surgery and can be a good alternative to misoprostol. TRIAL REGISTRATION: Iranian Registry Clinical Trial (IRCT) Identifier: IRCT2015112821506N4