A 24-year-old woman presents with vaginal bleeding 10 weeks after a term delivery. β-hCG is 85,000 mIU/mL. Ultrasound shows a heterogeneous intrauterine mass invading the myometrium with loss of uterine serosa intact. Chest X-ray shows two pulmonary nodules < 3 cm. Her WHO/FIGO score is calculated as 6. She is treated with single-agent methotrexate. At the third cycle, β-hCG plateau is detected. The next management step is:
- A Switch to actinomycin-D as second-line single-agent ✓
- B Continue methotrexate for two more cycles and reassess
- C Immediately add etoposide to methotrexate
- D Proceed to hysterectomy for drug-resistant GTN
Correct answer: A. Switch to actinomycin-D as second-line single-agent
Explanation
In low-risk GTN (WHO score ≤ 6) treated with methotrexate, resistance is defined as a β-hCG plateau (< 10% decline over three weekly values) or rise. The standard next step is to switch to alternative single-agent chemotherapy — actinomycin-D — which achieves remission in approximately 75% of methotrexate-resistant low-risk cases. Multi-agent regimens (EMA-CO) are reserved for failure of second-line single agents. Hysterectomy is not the first response to resistance in a young woman desiring fertility.
Reference: Shaw's Textbook of Gynaecology, 17th ed.
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Written and medically reviewed by the StethoPrep medical team.