Short-term efficacy and safety of early medical abortion in Japan: A multicenter prospective study

Abstract

Purpose: To evaluate the short-term efficacy and safety of a combined mifepristone-misoprostol regimen in individuals seeking medical abortion at up to 63 days of gestational age.

Methods: This open-label, multicenter, prospective study evaluated the short-term efficacy and safety of medical abortion, with the primary outcome being the abortion success rate 24 h after misoprostol administration. The participants received 200 mg of mifepristone orally and 800 μg of misoprostol buccally in the hospital/clinic 36-48 h later. Bleeding and lower abdominal pain, which are the main symptoms associated with medical abortion, were recorded.

Results: The abortion success rate was 93.3% (95% confidence interval [CI]: 87.3-97.1%) within 24 h of misoprostol administration, 63.3% (95% CI: 54.05-71.94%) within 4 h, and 90.0% (95% CI: 83.18-94.73%) within 8 h. The median time from misoprostol administration to a successful abortion was 3.93 h. Bleeding was most commonly observed 0-4 h prior to the confirmation of gestational sac (GS) expulsion. The most intense lower abdominal pain occurred 0-1 h before the confirmation of GS expulsion.

Conclusion: The combined regimen of mifepristone and buccal misoprostol for medical abortion showed short-term efficacy and a favorable safety profile.

Keywords: Japan; abortion; combination therapy; mifepristone; misoprostol.

FIGURE 1

Disposition of participants. The diagram shows disposition of participants in this study, including number of participants with successful abortion or unsuccessful abortion, and reasons for unsuccessful abortion.

FIGURE 2

Success rate at each timepoint with 4‐h increment after misoprostol administration. The success rate was 61.7% within the first 4 h and 26.7% between 4 and 8 h after misoprostol administration.

FIGURE 3

Cumulative incidence for the time to medical abortion from mifepristone administration. The success rate of medical abortion within 360 h after mifepristone administration was 93.8% (95% CI: 86.8–97.1%) based on the Kaplan–Meier estimate.

FIGURE 4

Time course of modified PBAC score before and after GS expulsion. Bleeding was tracked using the modified PBAC score. The mean (±SD) modified PBAC score was the highest 0–4 h prior to the confirmation of GS expulsion and then 0–4 h after the confirmation of GS expulsion; the modified PBAC score gradually decreased thereafter.

FIGURE 5

Time course of NRS score before and after GS expulsion. Lower abdominal pain was analyzed using the NRS. The most intense lower abdominal pain occurred 0–1 h before the confirmation of GS expulsion and then persisted at a consistent level until 3–4 h after the confirmation of GS expulsion.