Correlation of the volume of ectopic pregnancy and MTX therapy outcome: a retrospective cohort study.

Objective: To investigate a possible correlation between the volume of the tubal ectopic pregnancy (EP) measured by vaginal-ultrasound (VUS) and methotrexate (MTX) therapy outcome.

Study Design: Data of EP volume measured by one expert-sonographer, viability, clinical symptoms, previous IVF/insemination, follow-up of β-hCG and progesterone levels, and treatment of EP was collected of 100 patients with sonographically diagnosed EP, who attended the Department of Obstetrics and Gynecology of the Medical University Vienna between March 2008 and September 2011.

Results: The mean volume of EP (mVol.) in the group with successful MTX therapy (n = 38) was 5.11 ml, 95%CI [2.4; 7.8] with a median 3.2 ml, IQR [5.0], in the group with unsuccessful MTX treatment (n = 11) it was 15.24 ml, 95%CI [-2.6; 33.1], with a median 4.4 ml, IQR [11.4]. We could observe a trend towards a lower mVol. in the successful MTX group (5.11 ml vs. 15.24 ml). We could not show a significant correlation (u-test p = 0.208).

Conclusion: A clear tendency was observed towards a lower mVol. in the successful MTX therapy group, but we could not verify a statistically significant correlation of volume of EP and MTX therapy outcome most likely due to the small sample size. This was the first study investigating the correlation of volume of EP and MTX therapy outcome as principal question.