What medication should be prescribed for a patient with an ectopic pregnancy?

Methotrexate for Ectopic Pregnancy Treatment

For a patient with confirmed ectopic pregnancy, the provider should prescribe methotrexate (Option A), provided the patient meets specific eligibility criteria for medical management. 1

Patient Eligibility Assessment Before Prescribing

Before prescribing methotrexate by phone, the provider must verify the following criteria are met:

• Hemodynamic stability - Patient must have stable vital signs with no signs of rupture 1
• Ectopic mass size ≤3.5 cm in greatest dimension on ultrasound 1
• β-hCG levels preferably ≤5,000 mIU/mL (success rates are significantly higher below this threshold) 1
• No embryonic cardiac activity on ultrasound (this is a relative contraindication) 1
• Patient ability and willingness to comply with close follow-up - This is critical as treatment failure occurs in 3-36% of cases 1

Required Pre-Treatment Laboratory Testing

The provider must ensure these labs are obtained before prescribing: 1

• Complete blood count with differential and platelet counts
• Liver enzyme levels
• Renal function tests

Absolute Contraindications to Verify

Do not prescribe methotrexate if the patient has: 1

• Alcoholism
• Immunodeficiency
• Peptic ulcer disease
• Active disease of lungs, liver, kidneys, or hematopoietic system
• Ectopic gestational sac >3.5 cm

Methotrexate Dosing Protocol

The standard dose is 50 mg/m² intramuscular injection 1. A second dose may be required if β-hCG levels don't decrease appropriately on follow-up 1.

Critical Patient Instructions When Prescribing

The provider must instruct the patient to: 1, 2

• Return immediately for severe abdominal pain - this may indicate rupture, which occurs in up to 9% of methotrexate-treated patients 2
• Watch for signs of hemodynamic instability, heavy vaginal bleeding, or shoulder pain (indicating diaphragmatic irritation from blood) 1
• Avoid folic acid supplements and prenatal vitamins (they counteract methotrexate's action as a folate antagonist) 1
• Avoid aspirin and NSAIDs due to potentially lethal drug interactions 1
• Discontinue breastfeeding immediately if nursing, and wait at least 3 months after the last dose before resuming 1

Important Clinical Pitfalls

The median time to rupture after methotrexate administration is 14 days (maximum 32 days), so patients remain at risk even after treatment begins 2. The provider must emphasize that gastrointestinal side effects from methotrexate (nausea, abdominal pain) can mimic acute ectopic rupture - rule out rupture before attributing symptoms to drug toxicity 3.

Treatment Success Rates and Failure Risk Factors

Success rates range from 65-96% overall 1. Higher failure risk is associated with: 1

• β-hCG levels >5,000 mIU/mL
• Larger ectopic masses (>3.5 cm)
• Presence of embryonic cardiac activity

Special Consideration for Rh-Negative Patients

For Rh-negative women, anti-D immunoglobulin must be administered due to the risk of alloimmunization 1.

When NOT to Prescribe Methotrexate by Phone

If the patient does not meet the strict eligibility criteria above, or if the provider cannot verify hemodynamic stability, ultrasound findings, and laboratory results, surgical management should be arranged instead rather than prescribing methotrexate remotely 3. The 5-15% of patients who require surgery after methotrexate failure often present with rupture 3, making careful patient selection critical.