Objective: To investigate the efficacy of single-dose methotrexate treatment and the factors affecting its success in the treatment of ectopic pregnancy.

Methods: Ectopic pregnancy cases treated with single dose methotrexate treatment between January 2013 and December 2017 were compared as successful and unsuccessful. Demographic characteristics of patients, ectopic mass size, beta human chorionic gonodotropin (β-hCG) values at the beginning of treatment and at 4th and 7th days were evaluated.

Results: A total of 462 patients, who underwent single dose methotrexate treatment as initial ectopic pregnancy treatment, were included in the study. Single dose methotrexate treatment was successful in 350 patients (75.8%) and failed in 112 patients (24.2%). Serum β-hCG levels on the day of methotrexate administration, β-hCG values at 4th day and at 7th day, and ectopic mass size were significantly higher in the failed group (p<0.001).

Conclusion: There are a number of factors affecting the success of single dose methotrexate treatment in ectopic pregnancy in hemodynamically stable patients. The most important of these are ectopic mass size and initial β-hCG value.