A 28-year-old woman with laparoscopically confirmed stage II endometriosis has a serum CA-125 level of 65 U/mL. She asks whether this test can be used to diagnose her disease. What is the correct interpretation of CA-125 in endometriosis?
- A It is normal in all stages of endometriosis
- B Levels above 35 U/mL confirm endometriosis with high specificity
- C It may be modestly elevated but lacks sensitivity and specificity for diagnosis ✓
- D It correlates directly with rASRM stage and can replace staging
Correct answer: C. It may be modestly elevated but lacks sensitivity and specificity for diagnosis
Explanation
CA-125 is derived from coelomic epithelium and is frequently modestly raised in endometriosis, but it also rises in menstruation, pregnancy, pelvic inflammatory disease, fibroids and epithelial ovarian cancer. Its sensitivity and specificity are too poor for diagnosis or staging, so guidelines advise against using it as a diagnostic test. It is occasionally used to follow response or recurrence in advanced disease.
Reference: Williams Gynecology, 4th ed.
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Written and medically reviewed by the StethoPrep medical team.