Pregnancy of Unknown Location in a Cohort of Patients Treated With Methotrexate [17I

Abstract

INTRODUCTION: To determine the prevalence of pregnancy of unknown location (PUL) in patients treated with Methotrexate (MTX) for nonsurgical diagnosis of ectopic pregnancy (EP). To determine the beta-hCG treatment outcomes. METHODS: IRB approved retrospective cohort study of patients who received MTX for treatment of EP over a 10-year period in an urban-based healthcare system. Wilcox test was used for statistical analysis. RESULTS: A total of 150 pregnancies were identified as treated with MTX over a 10-year period. Pregnancies were classified based on reviews of ultrasound as pregnancy of unknown location (PUL), ectopic pregnancy (EP), or Intrauterine pregnancy (IUP). 47 were classified as PUL, 101 EP, 2 IUP. Approximately 1/3 of patients treated with MTX were PULs. The average baseline beta-hCG was 2960 MIU/ML and the average B-hCG at treatment was 4188 MIU/ML for the entire cohort. Resolution of beta-hCG levels with one dose of MTX differed between pregnancy types with PULs prescribed MTX at a lower B-hCG level on day of treatment (56% vs 27% at beta-hCG of less than 1000 MIU/ML) compared to EP. Additionally, 61% of the entire cohort were treated with 2 data points or less. 38% of PUL were treated with 1 to 2 beta-hCG values and 82% PUL were treated at beta-hCG <2000 MIU/ML. Of the two IUPs, beta-hCG level at treatment was 6267 MIU/ML and 13353 MIU/ML. CONCLUSION: There may be an underappreciated risk of inadvertent administration of Methotrexate to patients with early IUP. A minimum of three beta-hCG assays over seven days in the diagnostic algorithm for EP would decrease treatment of PUL.