Faster Complete Abortion With Reduced Interval Between Mifepristone and Misoprostol

SAN FRANCISCO — A reduced time from mifepristone to misoprostol during the second trimester significantly reduced the time from mifepristone to complete abortion, a prospective randomized controlled trial in Israel found.

With the standard 24-hour mifepristone-misoprostol regimen, the median time from mifepristone to complete fetal expulsion was 33 hours, while it was 24.5 hours with a reduced 12-hour regimen (P<0.001). However, the median time from misoprostol to complete abortion was 3 hours longer in the 12-hour group compared with the 24-hour group (12.5 hours vs 9.5 hours, P=0.028), reported Raanan Meyer, MD, of Cedars-Sinai Medical Center in Los Angeles at the American College of Obstetricians and Gynecologists (ACOG) annual meeting.

“The main takeaway is a 24-hour interval provides 3-hour shorter induction time and overall 8.5-hour longer total abortion time compared to 12-hour,” Meyer concluded, adding that “these findings can aid in shared decision-making prior to medical abortion in the second trimester.”

“For patients who are in the middle of having an abortion, just the idea of knowing that you’re in the middle of something, I think it’s emotionally very draining. So knowing that you can do everything shorter is better,” Meyer told MedPage Today.

Meyer noted that a shorter abortion time can improve patients’ experience while decreasing hospitalization time. The current recommended interval between mifepristone and misoprostol is between 24 and 48 hours.

At 12 hours following the first misoprostol dose, 45% of the 12-hour regimen group and 62.5% of the 24-hour group had completed abortion. At the 24-hour mark, those rates were 75% and 90%, respectively. By 48 hours, both groups reached 97.5%.

In the 24-hour group, 15% needed either additional misoprostol or oxytocin and/or cervical preparation, as did 22.5% of the 12-hour group. Rates of side effects, pain scores, and satisfaction were similar between the two groups.

Paul Blumenthal, MD, MPH, of Stanford University, who was primary investigator of the trial, told MedPage Today that in the U.S., the length of a hospital stay for an induction abortion depends on the timing of when each medication is given.

Blumenthal explained that a person “might get mifepristone as an outpatient, then they’re on their own until they’re told to report for the actual beginning of the labor induction.”

“In the U.S., it’s hard to find a center that does enough induction abortions to really do a randomized controlled trial because we don’t do that many induction abortions — we tend to do more D&Es [dilation and evacuations],” Blumenthal explained.

For this randomized controlled trial, 80 women seeking a second-trimester medication abortion were randomized to either receive misoprostol 24 hours or 12 hours after mifepristone administration, with 40 women in each group. Enrollment went from July 2020 to June 2023.

The primary outcome was time from the first misoprostol dose to fetal expulsion. Secondary outcomes included mifepristone-to-abortion time, the percentage of fetal expulsion at 12, 24, and 48 hours, as well as side effects, pain, and satisfaction scores.

Baseline characteristics of participants in both groups were comparable, with average age in the early 30s, BMI of about 25, and a gestational age of about 24 weeks.

Meyer noted several limitations, including that the study was not powered to evaluate secondary outcomes and the studied population only included Hebrew-speakers, which can limit generalizability. Also, satisfaction scores were not obtained from all patients, and postpartum curettage was done in all cases prior to 24 weeks, which is not standard in all countries.

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