Objectives: To evaluate the effectiveness of systemic methotrexate in the treatment of interstitial pregnancy.
Design: Prospective observational study.
Setting: An Early Pregnancy Assessment Unit in a London teaching hospital.
Sample: Twenty consecutive women diagnosed with an interstitial pregnancy.
Methods: Women were diagnosed with an interstitial pregnancy based on transvaginal ultrasound findings. Single dose, intramuscular methotrexate was administered on day 0. A second dose of methotrexate was given if the beta-hCG levels had not fallen by 15% between days four and seven. Weekly follow up continued until the serum beta-hCG < 5 IU.
Main outcome measure: The resolution of serum beta-hCG levels without the need for surgical intervention.
Results: Two hundred and ninety-three ectopic gestations were diagnosed over a 42-month period. Twenty of these were interstitial in nature, with a median initial serum beta-hCG of 6452 IU. Of the 20 interstitial pregnancies, 17 cases received systemic methotrexate. Sixteen were treated successfully (94%), including all of the four cases with fetal heart activity present. A second methotrexate dose was given to six patients. Two cases were managed expectantly. Two cases underwent laparotomy and cornual resection: one elected for surgical management at the outset and one as a result of suspected ectopic rupture after two doses of methotrexate. There were no other complications.
Conclusions: Systemic methotrexate is a safe and highly effective treatment for interstitial pregnancy. Surgery can be avoided in the majority of women with this condition. Early recognition of the cornual pregnancy with transvaginal ultrasound is essential.