CLINICAL ORAL ABSTRACTS

Introduction To compare immediate versus delayed initiation of medication abortion (MAB) among patients with undesired pregnancy of unknown location (PUL). Method This retrospective cohort study used electronic medical record data from Planned Parenthood League of Massachusetts (2014–2019) to compare time to diagnosis of pregnancy location among patients requesting MAB with an LMP of Results Of 5619 eligible MAB visits, 452 patients had a PUL (8.0%). Three patients underwent uterine aspiration, 55 same-day-start and 394 delay-for-diagnosis. Among the 359 (80%) with a pregnancy location diagnosis, median days-to-diagnosis was 5.0 (IQR: [5.0, 13.0]) for same-day-start and 8.0 (IQR: [3.0, 9.0]) for delay-for-diagnosis (p = 0.020). Thirty patients (6.6%), all in the delay-for-diagnosis group, were treated for ectopic pregnancy and 4 ectopics ruptured. Twenty-four percent (13/55) of same-day-start and 33% (129/394) of delay-for-diagnosis patients visited an emergency department (p = 0.216). Of those who received mifepristone, the ongoing pregnancy rate was 9.1% (5/55) for same-day-start versus 1.9% (3/161) for delay-for-diagnosis (p = 0.027). Loss-to-follow-up without a diagnosis was 21.8% versus 16.2% among same-day versus delayed-for-diagnosis, respectively (p = 0.447). Conclusions In patients with undesired PUL, immediate initiation of medication abortion excludes ectopic pregnancy more rapidly than delay-for-diagnosis, with no impact on follow-up rates, but lower abortion efficacy.