A comparison of isosorbide mononitrate and misoprostol cervical ripening before suction evacuation

Abstract

Objective: To compare the efficacy of a nitric oxide donor (isosorbide mononitrate) and a prostaglandin E1 analogue (misoprostol) for cervical priming before suction termination of pregnancy.

Methods: This was a randomized, double blind, placebo-controlled trial. One hundred twenty-six healthy women requesting termination of pregnancy between 9 and 12 weeks' gestation were recruited. Women were randomized into three groups: control, isosorbide mononitrate, and misoprostol. All women were given moistened intravaginal study drugs (placebo, 40 mg of isosorbide mononitrate, or 400 microg of misoprostol) 4-6 hours before suction evacuation. Side effects were assessed 3 hours after drug administration. The cervical dilatation and the cumulative force required to dilate the cervix to 8 mm were measured by a cervical tonometer before suction evacuation. Operative blood loss was measured after sieving off the products of gestation.

Results: There were no differences in the baseline cervical dilatation, cumulative force, and operative blood loss between the isosorbide mononitrate and placebo groups. However, women in the misoprostol group had a significantly greater cervical dilatation, required less cumulative force, and had less blood loss than women in the isosorbide mononitrate or control group. The majority (more than 80%) of women in all three groups found their cervical priming agents acceptable.

Conclusion: Intravaginal isosorbide mononitrate was less effective than misoprostol in cervical ripening before suction termination of pregnancy.