What medication is used to resolve an ectopic (tubal) pregnancy?

From the Guidelines

Methotrexate is the primary medication used to treat ectopic pregnancy without surgery, with a standard regimen of a single intramuscular injection of 50 mg/m² of body surface area, and is most effective for early ectopic pregnancies with a mass smaller than 3.5 cm, no fetal cardiac activity, and hCG levels below 5,000 mIU/mL 1.

Key Considerations for Methotrexate Treatment

• The decision to administer methotrexate or use another treatment approach is complex and depends on various factors, including the size of the ectopic pregnancy, hCG levels, and the presence of fetal cardiac activity 1.
• Methotrexate therapy is contraindicated in patients with alcoholism, immunodeficiency, peptic ulcer, or active disease of the lungs, liver, kidneys, or hematopoietic system, and relatively contraindicated in patients with an ectopic gestational sac larger than 3.5 cm or with embryonic cardiac motion observed on ultrasound 1.
• Treatment success rates are also lower in patients who have a b-hCG level of 5,000 mIU/L or more 1.

Monitoring and Follow-up

• After receiving methotrexate, patients need close monitoring with hCG blood tests on days 4 and 7, then weekly until levels become undetectable 1.
• Patients should avoid alcohol, vitamins containing folic acid, NSAIDs, and sun exposure, as these can interfere with the medication's effectiveness or increase side effects 1.
• Patients should also abstain from sexual intercourse until hCG levels normalize 1.

Potential Complications

• Treatment failure, with rupture of the ectopic pregnancy, is one of the most serious complications of methotrexate therapy, and patients who develop increasing pain and/or signs of hemodynamic instability after methotrexate therapy should receive stabilizing care and prompt diagnostic studies to establish or exclude the diagnosis of ruptured ectopic pregnancy 1.
• Ruptured ectopic pregnancy must be considered in the differential diagnosis of patients who present to the ED with concerning symptoms or signs after methotrexate therapy 1.

From the Research

Medication for Ectopic Pregnancy

• Methotrexate (MTX) is a commonly used medication for the treatment of ectopic pregnancy, with a success rate of 68.5% in one study 2 and 91.5% in another study 3.
• The success of MTX therapy depends on various factors, including ultrasonographic findings, patient complaints, gestational week, and serum human chorionic gonadotropin (hCG) values 2.
• A single-dose protocol of MTX has been shown to be effective in 86.9% of cases, while two-dose and multi-dose protocols have lower success rates of 28.6% and 40%, respectively 2.
• The use of MTX has been found to be more effective in cases of low titers of beta-hCG and masses with a small diameter 4.
• A mathematical model has been developed to predict the success of MTX therapy based on the relative changes in serum beta-hCG concentration between the 1st and 4th days following MTX injection, with a cut-off value of 0.15 (15%) for a positive result 5.
• MTX therapy can be effective even in cases with high beta-hCG levels, as demonstrated by a case report of a patient with a high-beta-HCG ectopic pregnancy who was successfully managed with MTX 6.

Factors Affecting MTX Success

• Serum hCG values: higher values are associated with lower success rates of MTX therapy 2, 4.
• Gestational week: more advanced gestational weeks are associated with lower success rates of MTX therapy 2.
• Ultrasonographic findings: the presence of fetal cardiac activity and larger gestational sac diameters are associated with lower success rates of MTX therapy 2.
• Patient complaints: the presence of abdominal-pelvic pain is associated with lower success rates of MTX therapy 2.