How accurate are blood tests for diagnosing endometriosis?

EVIDENCE-BASED ANSWER Using different thresholds, CA-125 has positive likelihood ratios between 5 and 7.2, making it a moderately good test for ruling in endometriosis in patients with a high pretest probability. A relatively high negative likelihood ratio (0.5) limits its ability to rule out endometriosis. Antiendometrial autoantibodies, CA-19.9, and interleukin-6 are neither sensitive nor specific enough to be considered useful in the evaluation for endometriosis (SOR: B, metaanalyses of lower quality diagnostic studies).