Effect of isosorbide mononitrate for cervical ripening before surgical termination of pregnancy in the first trimester.

Objective: To evaluate the efficacy of isosorbide mononitrate (IMN) for cervical ripening prior to first trimester surgical termination of pregnancy.

Methods: A prospective, double-blind, randomized, placebo-controlled trial. Women scheduled for surgical termination of a nonviable fetus before 12 weeks of gestation from October 2008 to June 2009 were enrolled and randomly assigned to receive either 20 mg vaginally of IMN (n=24) or a placebo (n=24) 4 hours before suction evacuation. Cervical dilation before evacuation was assessed with 10-mm Hegar dilators followed by smaller sizes that were measured until the instrument passed freely through the internal os. Cervical dilation, adverse effects, termination complications, and patient satisfaction were the main outcomes.

Results: Mean cervical dilation was not significantly different between the IMN and placebo groups (6.29+/-0.99 mm vs 5.71+/-1.04 mm; P=0.05). Mean operative time did not differ between the groups (16+/-0.07 min vs 18+/-0.06 min; P=0.55), nor did patient satisfaction measured by visual analogue scale (7.04+/-1.68 vs 6.54+/-1.22; P=0.24).

Conclusion: IMN was comparable to placebo in terms of efficacy and patient satisfaction for cervical priming prior to first-trimester termination of pregnancy.