A 28-year-old woman presents with 6 weeks of amenorrhea, right lower abdominal pain, and vaginal spotting. Transvaginal ultrasound shows an empty uterus with a 3.5 cm gestational sac in the right adnexa. β-hCG is 8,500 mIU/mL. She is hemodynamically stable with no signs of rupture. What is the drug of choice for medical management of this ectopic pregnancy?

Explanation

## Medical Management of Unruptured Ectopic Pregnancy **Key Point:** Methotrexate is the gold-standard drug of choice for medical management of hemodynamically stable, unruptured ectopic pregnancies with appropriate selection criteria. ### Mechanism of Action Methotrexate is a dihydrofolate reductase inhibitor that arrests cell division in the S phase by blocking DNA synthesis. It is particularly effective against rapidly dividing trophoblastic tissue. ### Eligibility Criteria for Medical Management - Hemodynamically stable patient - Unruptured ectopic pregnancy - β-hCG typically <5,000 mIU/mL (though up to 10,000 mIU/mL may be acceptable) - No contraindications to methotrexate - Reliable follow-up available - Ectopic mass <3.5–4 cm ### Methotrexate Dosing Regimens | Regimen | Dose | Frequency | Success Rate | Notes | |---------|------|-----------|--------------|-------| | **Single-dose** | 50 mg/m² IM | Once | 88–96% | First-line; preferred | | **Two-dose** | 50 mg/m² IM | Days 0 & 4 | 94–98% | For higher β-hCG | | **Multi-dose** | 1 mg/kg IM | Days 1, 3, 5, 7 + folinic acid | 98–100% | Reserved for very high β-hCG | **High-Yield:** Single-dose methotrexate (50 mg/m² IM) is the most commonly used and preferred regimen in India and most guidelines for uncomplicated cases. ### Monitoring After Methotrexate 1. β-hCG on day 4 and day 7 2. If β-hCG drops >15% between days 4–7, weekly monitoring until undetectable 3. If <15% drop, consider second dose or surgical intervention 4. Avoid intercourse, NSAIDs, and alcohol during treatment **Clinical Pearl:** Patients must be counseled that resolution takes 2–6 weeks and β-hCG may transiently rise before falling. Ectopic rupture can still occur during medical management, so close follow-up is essential. ### Why Methotrexate Is Preferred - Proven efficacy with >90% success rate in appropriate cases - Avoids surgery and general anesthesia - Preserves tubal anatomy (important for future fertility) - Cost-effective - Outpatient management possible [cite:Jeffcoate's Principles of Gynaecology 8e Ch 8]