The ultrasonographic appearance of tubal pregnancy in patients treated with methotrexate

BACKGROUND: The aim of the present study was to evaluate the effect of methotrexate (MTX) treatment on the ultrasonographic appearance of extrauterine pregnancy (EUP) and, particularly, to test the hypothesis that the ultrasonographic appearance is not predictive of treatment success. METHODS: A prospective cohort study. The study group included 56 women with tubal EUP who received a single-dose protocol of MTX. EUP was diagnosed whenever an intrauterine gestational sac was not identified by transvaginal ultrasonography (TVUS), accompanied by an abnormal rise or plateau in hCG concentration. Serial TVUS was performed weekly until hCG normalization or the size of the ectopic mass declined to 1 cm(2). RESULTS: Ectopic tubal mass was identified on TVUS in 45 (80%) women with a mean size of 4 +/- 0.5 cm(2). Following the first week of MTX injection, the mean size of the ectopic mass significantly increased to 6 +/- 0.8 cm(2) (p = 0.02). The initial size of the ectopic mass was not related to the success of the treatment nor to serum hCG levels. Ultrasonographic resolution of the ectopic mass was documented in 27 women following a mean of 42 +/- 2.4 days (range 7-63 days). CONCLUSIONS: The initial size of a tubal pregnancy is not related to the success of MTX treatment. MTX treatment in tubal pregnancy is followed by an initial increase in the size of the ectopic mass. Accordingly, such enlargement of the ectopic mass should not be considered as a higher risk for failure of treatment.