Nomogram to predict methotrexate treatment success in ectopic pregnancy

Objective

To evaluate clinical factors prior to methotrexate (MTX) treatment for tubal ectopic pregnancy and to apply the data to a prediction model for treatment success.

Methods

A retrospective cohort study was conducted during 2014–2022. Of the 808 patients with a tubal ectopic pregnancy, 372 with a β-hCG level less than 5000 IU/L were treated with a single dose of MTX and were included in this study. Pretreatment factors, including patient characteristics, initial β-hCG level, and sonographic parameters, were compared between those who achieved complete resolution and those who needed additional MTX or surgical intervention. A logistic regression model and multivariable analysis were used to predict success. A graphic nomogram was generated to represent the model.

Results

Complete resolution of the ectopic pregnancy was achieved in 290 (77.9%) patients after a single dose of MTX. A second dose or surgical intervention was required for 82 (22.0%): 49 (13.2%) received a second dose of MTX and 33 (8.9%) underwent laparoscopic salpingectomy. In the MTX Success group compared to the MTX Failure group, the median β-hCG levels were lower (746 vs 1347 IU/L, P < 0.001) and the presence of a yolk sac and a fetal pole were less frequent. The predictive model, based on significant variables, includes initial β-hCG concentration and the visibility of a yolk sac or fetal pole. Analysis with cross-validation techniques revealed that the model was both accurate and discriminative.

Conclusion

A predictive nomogram was developed to predict the success of single-dose MTX treatment for tubal ectopic pregnancy.