A 27-year-old woman is confirmed to have a 3 cm left tubal ectopic pregnancy. She is hemodynamically stable, β-hCG is 1800 mIU/mL, no cardiac activity on ultrasound, and no contraindications to methotrexate. Single-dose methotrexate is administered. On day 4 post-treatment, the β-hCG is 1950 mIU/mL. What is the CORRECT interpretation and action?

• A Treatment failure; proceed to surgery immediately
• B Treatment success; repeat methotrexate is not needed
• C Rupture has occurred; emergency laparotomy
• D Expected post-treatment rise; monitor β-hCG on day 7 ✓

Explanation

After single-dose methotrexate for ectopic pregnancy, a transient rise in β-hCG between days 1 and 4 is expected and does not indicate treatment failure; this is due to trophoblastic cell lysis releasing β-hCG into the circulation. Treatment success is assessed by comparing day 4 and day 7 β-hCG levels; a ≥15% decline from day 4 to day 7 indicates successful response. Surgery or a second dose is indicated only if this criterion is not met.

Reference: Williams Obstetrics, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.