A woman at 8 weeks gestation requests medical abortion. She is prescribed mifepristone 200 mg orally followed 48 hours later by misoprostol 800 mcg vaginally. The mechanism of mifepristone in this regimen is:

• A Direct uterotonic action causing myometrial contractions
• B Inhibition of aromatase reducing oestrogen support of endometrium
• C Prostaglandin synthesis stimulation via COX-2 pathway
• D Progesterone receptor blockade leading to decidual necrosis and cervical softening ✓

Explanation

Mifepristone is a synthetic 19-norsteroid with potent antiprogesterone activity. It competitively blocks progesterone receptors, causing decidual disruption, increase in endogenous prostaglandin sensitivity, cervical ripening, and release of the implanted conceptus. This primes the uterus for subsequent misoprostol-induced contractions. The combined regimen is >95% effective at gestations ≤9 weeks.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.