A woman is diagnosed with an unruptured ectopic pregnancy at 6 weeks: adnexal mass 3.2 cm, beta-hCG 1800 mIU/mL, no fetal cardiac activity on transvaginal ultrasound. She is hemodynamically stable. What criteria MUST be met for single-dose methotrexate (50 mg/m²) to be appropriate?

• A hCG <10,000 mIU/mL, mass <5 cm, cardiac activity absent
• B hCG <2000 mIU/mL regardless of mass size
• C Any ectopic if the patient is stable and declines surgery
• D hCG <5000 mIU/mL, mass ≤3.5 cm, no cardiac activity, hemodynamically stable, no contraindication to methotrexate ✓

Explanation

ACOG criteria for single-dose methotrexate in ectopic pregnancy require: hemodynamic stability, ectopic mass ≤3.5 cm (some guidelines allow ≤4 cm), beta-hCG <5000 mIU/mL, absence of fetal cardiac activity, and no contraindications (renal/hepatic dysfunction, thrombocytopenia, immunodeficiency, active pulmonary disease, breastfeeding). Success rates are 90% when hCG <5000; below 80% when hCG 5000–10,000, and poor beyond 10,000 mIU/mL. This patient (hCG 1800, mass 3.2 cm, no cardiac activity) meets criteria.

Reference: Williams Obstetrics, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.