Conservative Treatment of Interstitial Ectopic Pregnancy with the Combination of Mifepristone and Methotrexate: Our Experience and Review of the Literature.

Introduction: Interstitial pregnancy (IP) is an ectopic pregnancy (EP) located in the portion of the fallopian tube that penetrates the uterine muscular layer. Incidence increased in the last two decades with the widespread use of the assisted reproductive techniques. It is estimated in 1-6% of all the EPs, with a maternal mortality rate of 2.0-2.5%. Clinical presentation, gestational age at diagnosis, beta-human chorionic gonadotropin (-hCG) levels, ultrasound features, and patient preference, should be considered to determine the best management: surgical, medical treatment, or close observation. We report two cases of IP successfully managed with systemic MTX and Mifepristone: in one case -hCG was >10.000 mIU/mL and a vital embryo was present.

Materials And Methods: A literature search was carried out on MEDLINE, EMBASE, and PUBMED. We identified two cases of IP referred to the Institute for Maternal and Child Burlo Garofolo, Trieste. Data related to clinical presentation, -hCG, and ultrasound scan at the moment of the diagnosis were recorded. In one of the cases, the -hCG level was >10.000 mIU/mL, and a vital embryo was testified at an ultrasound scan. The patient was asymptomatic and she was treated using multidose systemic Methotrexate (MTX) combined with Mifepristone. In the second case, in the presence of a clinically stable patient with - hCG > 10.000 mIU/mL, it was chosen that the administration of Mifepristone combined with a double dose of MTX. -hCG levels and ultrasound examinations were performed weekly until a complete resolution of the IP.

Results: In the first case, -hCG dropped down in 5 days and became undetachable in 30 days. In the second case, -hCG became undetectable in 47 days. The first-line therapy in asymptomatic women could be addressed to a combined protocol, consisting of a systemic multidose MTX regimen with a single oral dose of Mifepristone.

Conclusions: Clinical management of IP remains a debated topic. In selected cases, a systemic multidose MTX regimen combined with a single oral dose of Mifepristone could be considered also in the presence of high serum -hCG.