A woman with low-risk GTN (FIGO score 4) is started on single-agent methotrexate and folinic acid rescue (8-day regimen). After 2 courses, her hCG plateau persists. What constitutes resistance requiring a change to multi-agent therapy?

• A hCG rise of 5% after the second course
• B Failure of hCG to fall by at least 1 log after the second course ✓
• C Any detectable hCG after the first course
• D hCG plateau for 3 measurements during the second course

Explanation

Resistance to single-agent chemotherapy in GTN is defined as failure of hCG to fall by at least 1 log (i.e., 10-fold) within one course, or a plateau or rise of hCG during treatment. Failure of 1-log fall after a course is the classic threshold requiring escalation to multi-agent regimens such as EMA-CO (etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine). A 5% rise is not the threshold; a 1-log drop failure is.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.