Predictors of single-dose methotrexate treatment success in ectopic pregnancies: A retrospective cohort study

Objective

The present study investigated the predictors of single-dose (50 mg/m²) methotrexate (MTX) treatment success in ectopic pregnancies.

Method

A retrospective cohort study was conducted using information databases from a single academic tertiary care hospital among 396 participants referred for treatment of ectopic pregnancy (EP). Data were collected on age, history of EP, basal level of β-hCG, features of vaginal ultrasound (left or right), mass size, presence of hematoma around the mass and free pelvic fluid, and demand of subsequent doses of MTX or surgery. The patients were divided into success and failure groups based on whether they were treated with a single-dose of methotrexate (single dose MTX), or required subsequent doses of MTX or surgery.

Results

The success rate of single-dose MTX treatment was approximately 74%. The failure chance was significantly higher in right adnexal masses (OR: 3.45), history of EP (OR: 28.19), presence of hematoma on ultrasound (OR: 26.69), and serum β-hCG > 719 mIu/ml (OR: 5.19). A mass size > 19 mm was associated with a 79% increased chance of failure (p = 0.10). These variables accounted for approximately 45–66% of the failure variance for single-dose MTX treatment. Based on ROC curve analysis, initial β-hCG level of 719 mIu/ml was the best cutoff for patients with EP (with a sensitivity of 82% and specificity of 63%).

Conclusion

The treatment outcome of single dose MTX can be successfully predicted based on the previous history of EP, the presence of hematoma on ultrasound, mass location, and measurement of β-hCG levels before treatment.