Identification of hormonal parameters for successful systemic single-dose methotrexate therapy in ectopic pregnancy.

Single-dose methotrexate is an alternative to surgery in treating ectopic pregnancy. Because success rates vary, we sought to identify factors which predict treatment outcome. A total of 44 women with ectopic gestation were treated. The non-laparoscopic diagnosis of ectopic pregnancy was made following history, physical examination, ultrasound, endometrial biopsy and the measurement of serial beta-human chorionic gonadotrophin (HCG) and progesterone concentrations. Methotrexate (50 mg/m2 i.m.) was administered, with a second dose given 1 week later in patients with plateauing or rising beta-HCG concentrations. Of 44 patients, 23 (52.3%) were successfully treated with one dose. An additional 10 women (22.7%) were also successfully managed but required a second dose, giving an overall success rate of 75.0%. In all, 11 women (25.0%) required surgery, four of whom experienced tubal rupture. Receiver operator curves were constructed to optimally select pretreatment beta-HCG and progesterone cut-off concentrations for successful treatment. Using beta-HCG < 1500 IU/l or progesterone < 7.0 ng/ml (22.3 nmol/l) as a cut-off concentration produced a diagnostic test with a sensitivity of 87.5%, a specificity of 90.0%, a positive predictive value of 96.6% and a negative predictive value of 69.2%. Conversely, this model predicts that patients with serum beta-HCG concentrations > or = 1500 IU/l and progesterone concentrations > or = 7.0 ng/ml are at far greater risk of failing single-dose methotrexate therapy.