Nomogram for Predicting Methotrexate Failure in Tubal Ectopic Pregnancy: Time for Prospective Validation

Abstract

Methotrexate remains a standard nonsurgical option for stable, unruptured tubal ectopic pregnancy, but a meaningful proportion of patients fail medical therapy and require rescue intervention. Predicting who will fail treatment based on a single variable, such as β-hCG alone, has proven unreliable, prompting interest in multivariable nomograms that combine β-hCG levels and trends, ultrasound findings, gravidity, and prior ectopic history into a single bedside risk score. Such tools could theoretically allow earlier triage toward surgery for high-risk patients while supporting medical management for patients with a high likelihood of treatment success, which has been reported to exceed 85%. However, current nomograms for MTX failure are based largely on retrospective data, with inconsistent treatment protocols, variable definitions of failure, and limited sample sizes that may affect statistical power and generalizability. Prospective, multicenter validation across diverse populations, including those conceived through assisted reproductive techniques, is needed before these models can be broadly incorporated into clinical decision-making.