Ectopic pregnancy is a potentially life-threatening condition. While surgical approaches are the mainstay of treatment, advances in early diagnosis facilitated the introduction of medical therapy with methotrexate (MTX) in the 1980s . In one report, approximately 35 percent of women with ectopic pregnancy are eligible for medical treatment . Due to the routine use of early ultrasound among infertile patients who conceive, diagnosis of ectopic pregnancy can be established early and medical treatment can be administered in most cases. The overall success rate of medical treatment in properly selected women is nearly 90 percent [3-5].
Medical treatment of ectopic pregnancy will be reviewed here. Ectopic pregnancy diagnosis, surgical treatment and expectant management are discussed separately. (See "Clinical manifestations and diagnosis of ectopic pregnancy" and "Surgical treatment of ectopic pregnancy and prognosis for subsequent fertility" and "Expectant management of ectopic pregnancy".)
MTX is a folic acid antagonist widely used for treatment of neoplasia, severe psoriasis, and rheumatoid arthritis. It inhibits DNA synthesis and cell reproduction, primarily in actively proliferating cells such as malignant cells, trophoblasts, and fetal cells.
MTX is rapidly cleared from the body by the kidneys, with 90 percent of an intravenous (IV) dose excreted unchanged within 24 hours of administration .
The dose of MTX used to treat ectopic pregnancy (50 mg/m2 or 1 mg/kg) is relatively low. High dose MTX (≥500 mg/m2) is used to treat some malignancies.