SERUM PROGESTERONE AS A PREDICTOR OF METHOTREXATE SUCCESS IN THE TREATMENT OF ECTOPIC PREGNANCY

Objective: To determine the prognostic value of a single serum progest erone measurement for resolution of ectopic pregnancy following methot rexate therapy. Methods: All patients attending our infertility clinic had quantitative beta-hCG and serum progesterone measured prospective ly within the first week of missed menses. Ectopic pregnancy was diagn osed nonsurgically by poorly rising beta-hCG levels and lack of eviden ce of intrauterine gestation by transvaginal sonography. Once diagnose d, candidates received a single intramuscular injection of methotrexat e, 50 mg/m(2). Treatment outcome was categorized as either resolved or requiring surgery, and interpreted with respect to serum progesterone measured within 24 hours of methotrexate administration. Results: Twe nty-one patients were treated for ectopic pregnancy. Eleven had serum progesterone levels greater than 10 ng/mL and ten patients had levels of 10 ng/mL or less. The two groups did not differ significantly with respect to age, weight, hCG at the time of methotrexate administration , or amount of methotrexate administered. Of the 11 patients with seru m progesterone levels above 10 ng/mL, only five had pregnancies that r esolved following methotrexate. All ten patients with levels less than 10 ng/mL had resolution. This difference is significant (P = .009, 95 % confidence interval 0.26-0.84). There was no improvement in the pred iction of outcome when either the absolute or daily percentage increas e of hCG was determined before methotrexate administration. Conclusion : A single serum progesterone measurement above or below 10 ng/mL is u seful for predicting resolution of tubal pregnancy with methotrexate t reatment.