Interstitial Pregnancy Treated with Mifepristone and Methotrexate with High Serum β-hCG Level in a Patient Wishing to Preserve Fertility: Time to Define Standardized Criteria for Medical/Surgical Therapy?

Interstitial pregnancy (IP) accounts for 2% of all ectopic pregnancies and has a mortality rate of 2-2.5%. The diagnosis is made by a transvaginal ultrasound and the treatment can be medical or surgical. We report the case of a 36-year-old primigravida who was 6 + 5 weeks pregnant, diagnosed with interstitial pregnancy by ultrasound, who had a very high serum beta-hCG level (31,298 mIU/mL) and wanted to preserve her fertility. The patient was treated with one dose of mifepristone and a double dose of methotrexate since the decrease in the beta-hCG serum level was less than 15% after the first dose. At the beginning, medical therapy was effective, as no embryonal cardiac activity was detected and serum beta-hCG levels decreased early, but on the 20th day of hospitalization, the patient underwent surgery for her clinical symptoms and the evidence of free fluid in the Douglas pouch at a transvaginal ultrasound exam. Our experience showed that medical treatment should be considered, especially in women wishing to preserve their fertility. Further studies are needed to establish a standardized protocol and maybe a clinical score that can be useful in predicting the patients in which medical therapy could be most successful.

Automated summary

Interstitial pregnancy is a rare type of ectopic pregnancy, with diagnosis made by ultrasound and treatment options including medical or surgical intervention. This case report highlights the effectiveness of medical treatment, particularly for women seeking to preserve fertility. Further research is needed to establish standardized protocols and clinical scores for predicting successful outcomes in medical therapy.