Evaluation of shorter mifepristone to misoprostol intervals for second trimester medical abortion: a retrospective cohort study

To assess shorter mifepristone-misoprostol intervals compared to current guidelines for second trimester medical abortion on total abortion time (mifepristone to fetal expulsion) and induction time (first misoprostol to fetal expulsion).

This retrospective cohort study included women who elected for a second trimester medical abortion with mifepristone and misoprostol at an academic tertiary medical center in the United States from January 2008 to June 2018. We abstracted times of mifepristone administration, first dose of misoprostol, and fetal expulsion from the medical record. We assessed outcomes based on the shorter intervals <12 h and 12 to 24 h compared to the guideline mifepristone-misoprostol interval (24-48 h).

The study population included eighty-nine women, 47, 28, and 14 women in the <12 h, 12 24 h, guideline (24-48 h) groups, respectively. The cohort had a median gestational age of 22^0/7 weeks (range: 15^0/7-27^0/7) and parity of 1 (range: 0-5) with no differences observed between groups. Total abortion times were 20.7 h (range: 3.7-46.9), 30.6 h (16.7-48.0), and 42.8 h (32.7-62.6), respectively (p < 0.001). Induction times were 12.9 h (range: 1.2-36.6), 11.7 h (2.0-35.2), and 9.3 h (5.3-16.5), respectively. Fetal expulsion within 12 h of first misoprostol dose occurred in 22 (47%), 14 (50%), and 9 (64%), respectively (p = 0.52).

Shorter mifepristone-misoprostol intervals (less than 24 h) significantly decrease the total abortion time while maintaining a clinically similar induction time.

Shortening the mifepristone-misoprostol interval in second trimester medical abortion significantly decreases the total abortion time which may be preferable to some women or health systems.