A comparison of isosorbide mononitrate, misoprostol and combination therapy for first trimester pre-operative cervical ripening: a randomised controlled trial

Objective To determine whether a combined therapy with isosorbide mononitra te: (40mg) and misoprostol (400 mug) for pre-operative cervical ripening in the first trimester would result in improved clinical effectiveness, and f ewer side effects compared with each agent used alone. Design Randomised controlled trial. Setting Glasgow Royal Infirmary. Population Sixty-six primigravid women scheduled for suction termination of pregnancy. Methods Women were randomly assigned to receive before surgery, per vaginam , Isosorbide mononitrate 10 mg in = 22), misoprostol 400 mug (n = 22) or bo th agents together [isosorbide mononitrate 40 mg and misoprostol 400 mug] ( n = 22). Main outcome measures 1. To assess the cumulative force required to dilate the cervix to 8 mm: 2. the onset of new symptoms before termination of preg nancy. Results The cervical resistance following combination therapy with isosorbi de mononitrate and misoprostol was not significantly different than followi ng misoprostol alone [21.5N vs 18.5N; median difference (95% CI) 19N (-22 t o -19)]. Pre-treatment with misoprostol used alone resulted in a lower cerv ical resistance than isosorbide mononitrate alone (18.5N vs 39N, P = 0.04, Mann-Whitney U test). There was no difference in the number of women remain ing asymptomatic following either isosorbide mononitrate or misoprostol or combination therapy [14/22 (64%) vs 11/21 (52% vs 11/22 (50%), Fisher's exa ct test]. Conclusions We have not shown any advantage of combining misoprostol with t he nitric oxide donor isosorbide mononitrate compared with misoprostol alon e for pre-operative cervical ripening in the first trimester.