Interstitial Ectopic Pregnancy: The Role of Mifepristone in the Medical Treatment

Abstract

Interstitial pregnancy is defined as the presence of a gestational sac in the most proximal section of the fallopian tube. Management of interstitial pregnancy remains a debated topic. Depending on hemodynamic stability, size of pregnancy, depth of surrounding myometrium, and desires for future fertility, interstitial pregnancy can be managed medically or surgically. We reviewed the literature in December 2020 using keywords “interstitial pregnancy”, “medical treatment”, “methotrexate”, and “mifepristone”. Articles published from January 1991 until 2020 were obtained from databases EMBASE, SCOPUS, and PUBMED. We describe the case of a patient with an interstitial pregnancy that was managed with a total medical approach in August 2020 at Burlo Garofolo Hospital. The patient was asymptomatic and hemodynamically stable, with a high level of serum β-hCG (22,272 mUi/mL). We used the combination of methotrexate (MTX) and mifepristone. Medical therapy was effective leading to interstitial pregnancy resolution in 51 days without collateral effects for the patient. We found seven previous cases reported in the literature. Our purpose is to underline the efficacy of medical therapy with systemic multidose MTX associated with a single oral dose of mifepristone and also folinic acid when is present a viable fetus and a high serum β-hCG level.

Surgical Treatment Following Failed Medical Treatment of an Interstitial Pregnancy

“…Diagnosis of IP is becoming increasingly timely due to the better accuracy of the latest ultrasound systems [ 10 ]. Magnetic resonance imaging may be used if ultrasound is inconclusive, especially to differentiate it from an angular or intrauterine pregnancy [ 11 ]. In our case, ultrasound was performed by an expert operator and was conclusive for interstitial ectopic pregnancy.…”

“…However, the systemic route appears to be safer because of the high vascularization of the gestational sac [ 6 ]. The addition of a single dose of mifepristone was shown to improve success rates of the medical treatment [ 11 , 16 ]. Mifepristone is a competitive progesterone receptor antagonist, exerting its action through the detachment of the trophoblast from the uterine decidua, the degeneration of the corpus luteum, and the induction of uterine contractions.…”

Ruptured interstitial ectopic pregnancy: A case report and review of the literature

“…For medical treatment, intra-muscular injection of methotrexate is the method of choice [ 5 ]. Unlike the Fernandez score for tubal EP, there is no threshold value for serum β-hCG levels below which the drug should not be used [ 2 ]. Medical treatment is increasingly used nowadays with variable success rates, especially for unruptured interstitial pregnancies.…”

“…It is therefore to be differentiated from a cornual pregnancy, which corresponds to implantation in the cavity of a rudimentary horn of the uterus, which may or may not communicate with the uterine cavity. The risk factors for interstitial pregnancy are those of ectopic pregnancy, notably a history of ectopic pregnancy, pelvic inflammatory disease, pelvic surgery and assisted reproduction techniques [ 2 ].…”

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?

“…An MRI scan may be considered if ultrasound is insufficient for diagnosis [ 11 ]. Thanks to the use of increasingly precise, high-resolution instruments, diagnosis can be made promptly and more easily [ 12 ]. Interstitial pregnancies are characterized by high risk of severe hemorrhage and maternal morbidities.…”