A 32-year-old has serum β-hCG of 45,000 mIU/mL. Ultrasound shows a snowstorm appearance with no fetal parts. She undergoes suction evacuation for complete hydatidiform mole. Histology confirms diploid 46,XX chromosomal complement with diffuse trophoblastic proliferation, complete absence of fetal/embryonic tissue, and cisternae formation. Post-evacuation β-hCG plateaus at 2,400 mIU/mL for 3 consecutive weeks at 8 weeks post-evacuation. What is the diagnosis and next management step?

• A Normal post-molar regression; continue weekly hCG monitoring
• B Gestational trophoblastic neoplasia (GTN); initiate single-agent chemotherapy (methotrexate or actinomycin-D) ✓
• C Persistent GTN requiring hysterectomy as first-line treatment
• D Invasive mole requiring re-evacuation before chemotherapy

Explanation

WHO/FIGO criteria for diagnosing post-molar GTN (requiring chemotherapy) include any ONE of: (1) hCG plateau (< 10% change) for 4 or more values over 3 weeks; (2) hCG rise of ≥ 10% for 3 or more values over 2 weeks; (3) persistent hCG at > 6 months post-evacuation. This patient has a 3-week plateau at 8 weeks, meeting criterion 1. Risk scoring (FIGO/WHO) is performed next — she is likely low-risk (score ≤ 6), and single-agent chemotherapy (methotrexate or actinomycin-D) achieves > 98% cure. Hysterectomy is not first-line; re-evacuation has limited benefit and risks uterine perforation. Continued monitoring without treatment would miss the treatment window.

Reference: Williams Obstetrics, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.