Early prediction of methotrexate treatment outcome in tubal ectopic pregnancy based on days 0 and 4 human chorionic gonadotropin levels

Aim: Methotrexate (MTX) is an efficient treatment for ectopic pregnancy, used according to ‘single-dose’ protocol. Treatment success is evaluated on days 4 and 7 after dose administration, and defined as a decline of ≥15% in beta-human chorionic gonadotropin (β-hCG) levels, with a positive predictive value of 93%. A decrease on day 4 β-hCG levels was determined to be a good predictor for treatment success. We retrospectively examined changes in β-hCG levels between days 0 and 4 after MTX treatment as an early predictor for treatment outcome. Methods: The ‘success group’ consisted of patients with resolved ectopic pregnancy after a single MTX dose and ‘failure group’ included patients who required additional MTX doses or underwent surgery after the first dose. For each group, demographic and pregnancy data were analyzed as well as initial (admission day), days 0, 4 and 7 β-hCG levels. Results: Of 159 women included in the study, MTX treatment was successful in 117 patients (73.6%) while 42 patients (26.4%) were defined as treatment failure. In the success group, most patients (58.9%) demonstrated a decrease in β-hCG values between days 0 and 4 as opposed to the failure group in which an increase in β-hCG values was observed (76.2%). Decrease of >18% in β-hCG levels was predictive of treatment success (positive predictive value 92%). Increase in β-hCG values is less predictive of treatment failure with positive predictive value of 54%. Conclusion: Differences in β-hCG levels between days 0 and 4 may serve as an early predictor for treatment outcome.