Effect of letrozole on uterine tonus and contractility: A randomized controlled trial

摘要

Background: Letrozole inhibits estrogen production. It has been shown to increase efficacy in medical abortion when used with misoprostol. This study investigated if letrozole acts as an abortifacient due to a synergistic effect with misoprostol on uterine contractility. Study Design: Sixteen healthy women requesting surgical abortion were randomized to receive either no pretreatment or treatment with letrozole 7.5 mg daily for 3 days prior to the abortion. All women received misoprostol 400 mcg vaginally 3.5 h prior to surgery. Intrauterine pressure was measured for 30 min before and 3.5 h after misoprostol was given using an intrauterine pressure catheter. Main outcome measure was uterine contractility analyzed by repeated-measures analysis of variance. Results: At baseline, uterine contractions were absent and tonus was low. No significant difference was seen between the two groups in tonus (p=.818) or in contractility (p=.423) after misoprostol administration. Conclusion: Letrozole does not appear to act as an abortifacient through an effect on uterine contractility or increased sensitivity to misoprostol of the uterine myometrium.