Association between corpus luteum volume and the success of termination of pregnancy with mifepristone

Abstract Background: Mifepristone is a progesterone antagonist often used in medical termination of pregnancy. One of its targets is the corpus luteum, the main source of progesterone in initial pregnancy maintenance. Corpus luteum volume is related to serum progesterone levels. Objective: This study intended to evaluate whether there is an association between corpus luteum volume and the success rate of pharmacological termination of pregnancy with mifepristone and misoprostol. Methods: This was a prospective, longitudinal, observational study. 176 women deciding to terminate their pregnancy were included. At the first medical visit we confirmed the presence of a viable pregnancy with less than 10 weeks and estimated corpus luteum volume by transvaginal ultrasound. Medical termination of pregnancy protocol in our hospital consisted of oral mifepristone 200 mg followed (24 hours) by oral misoprostol 200 µg one pill every hour until a maximum of eight doses. At the reevaluation visit, we registered clinical data and confirmed the success of the procedure by vaginal ultrasound. Results: The success rate of medical termination of pregnancy was 95.5%. No differences regarding corpus luteum volume were observed between successful and unsuccessful termination of pregnancy groups. Conclusion: In our sample there was no association between corpus luteum volume and the success rate of medical termination of pregnancy.