A 24-year-old woman is diagnosed with a right tubal ectopic pregnancy. She is hemodynamically stable, β-hCG is 1,500 IU/L, no fetal cardiac activity, and the ectopic mass is 2.5 cm. She is started on single-dose methotrexate. At the day 4 visit, her β-hCG is 1,950 IU/L. At day 7, it is 1,620 IU/L. What is the correct interpretation of this trend?
- A Treatment has failed; proceed to surgery
- B A second dose of methotrexate is immediately required
- C This is an expected pattern; continue monitoring weekly ✓
- D Switch to multi-dose methotrexate protocol
Correct answer: C. This is an expected pattern; continue monitoring weekly
Explanation
A transient rise in β-hCG between day 1 and day 4 is expected with methotrexate due to release of hCG from dying trophoblast. The critical criterion is a decline of at least 15% between day 4 and day 7. Here the decline is (1950-1620)/1950 = 16.9%, which is adequate. Treatment should continue with weekly β-hCG monitoring until undetectable. Surgery or second dose is only indicated if the day 4-7 decline is less than 15%.
Reference: ACOG Practice Bulletin No. 191, 2018 (reaffirmed) ed.
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Written and medically reviewed by the StethoPrep medical team.