In first-trimester medical abortion (up to 9 weeks) using mifepristone 200 mg + misoprostol, which route and timing of misoprostol administration is associated with the highest complete abortion rate and fewest side effects according to WHO 2022 guidelines?

• A Sublingual 800 mcg misoprostol 24-48 hours after mifepristone
• B Vaginal 800 mcg misoprostol immediately after mifepristone
• C Oral 400 mcg misoprostol 48 hours after mifepristone
• D Buccal 800 mcg misoprostol 36-48 hours after mifepristone ✓

Explanation

WHO 2022 updated guidelines recommend buccal or sublingual 800 mcg misoprostol 24-48 hours after mifepristone 200 mg for medical abortion up to 12 weeks. Buccal administration offers comparable efficacy to sublingual (>95% complete abortion) but with fewer GI side effects (nausea, vomiting, diarrhea, chills) compared to sublingual, because the slower absorption with buccal route reduces peak plasma levels. The 24-48 hour interval allows antiprogestogenic priming of the cervix and decidua by mifepristone, maximizing uterotonic response to misoprostol. Oral misoprostol alone (without mifepristone) has significantly lower efficacy (75-80%).

Reference: Williams Obstetrics, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.