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

Objectives: 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.

Study design: 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.

Results: 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).

Conclusions: Serum hCG trends can help differentiate ectopic pregnancy from successful medication abortion, but cannot distinguish between ectopic and retained intrauterine pregnancy.

Implications: 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.