Change in hCG levels after very early medication abortion for pregnancy of unknown location or probable intrauterine pregnancy.

Objective: To evaluate changes in serum/plasma human chorionic gonadotropin (hCG) from baseline levels in very early medication abortion (VEMA) in pregnancies of unknown location (PUL) and probable intrauterine pregnancy (IUP) to confirm treatment success.

Methods: A prospective cohort was selected from the VEMA randomized controlled trial conducted at 26 sites across nine countries. Patients with a gestational age ≤42 days without confirmed IUP on ultrasound (n = 741) received medication abortion according to WHO guidelines, hCG was measured at mifepristone intake and repeated on day 7 (+/-2). Changes in hCG were analyzed to distinguish the trends associated with complete abortion versus ectopic pregnancy, ongoing pregnancy, and incomplete abortion.

Results: Among 533 cases with complete abortion, a decline in hCG level of ≥80% was observed in 96.8 of cases 7 (+/-2) days post-abortion. The mean hCG decline for complete abortions was 94% (CI: 93.2-94.9). None of the ectopic pregnancies 8 (1.7%) or ongoing pregnancies 21 (2.9%), showed a decline of ≥80%. Rising or insufficient decline (<80%) indicated ectopic and ongoing pregnancy. The hCG trend following complete abortion was significantly different from all other outcomes (p < 0.001), but trends did not distinguish between ectopic, ongoing pregnancy, or incomplete abortion.

Conclusions: A hCG decline of ≥80% within 7 (+/-2) days can effectively confirm complete abortion and rule out ectopic and ongoing pregnancies in early medication abortion. These results highlight the effectiveness of hCG monitoring as a reliable follow-up tool for managing VEMA without confirmed IUP.