hCG trends after mifepristone and misoprostol for undesired pregnancy of unknown location

To describe human chorionic gonadotropin (hCG) trends for patients with a pregnancy of unknown location (PUL) presenting for medication abortion by management strategy and outcome.This retrospective cohort study included patients presenting for medication abortion with a PUL at ≤42 days gestation managed with either (1) immediate mifepristone with serial hCG follow-up (same-day-start) or (2) hCG testing every 48 to 72 hours ± ultrasonography to confirm pregnancy location followed by treatment (delay-for-diagnosis). The primary outcome was percent hCG change over time between presentation and diagnosis, summarized using a multivariate regression model.Of the 55 same-day-start patients, none were treated for ectopic. The eight who eventually required suction curettage had median hCG percent changes (interquartile range) on days 3, 4, and 5 of +57% (-14 to 127; n = 2), +292% (226-353; n = 4), and +392% (n = 1), while the 41 successful medication abortions had declines of -64% (n = 1), -65% (-75 to -27; n = 17), and -77% (-85 to -68; n = 13). Of the 380 delay-for-diagnosis patients, the 30 ectopic pregnancies had day 3, 4, and 5 changes of +38% (-17 to 56; n = 14), +50% (17-71; n = 7), and +115% (87-177; n = 4). None of the ectopic pregnancies declined ≥50% by days 3 to 5. The hCG trend for ectopic pregnancies differed from successful medication abortions (p < 0.01), but not medication abortions with retained intrauterine pregnancies (p = 0.41).Serum hCG trends can help differentiate ectopic pregnancy from successful medication abortion, but cannot distinguish between ectopic and retained intrauterine pregnancy.Serial serum hCG testing is effective for confirming successful medication abortion and identifying patients requiring further follow-up among patients undergoing medication abortion for an undesired PUL.