Endometriosis: Use of a new CA 125 assay in the diagnosis of endometriosis

Serum CA 125 concentrations are elevated in some women with endometriosis; however, the low sensitivity and specificity of the assay have made it impractical to use it as a diagnostic test for endometriosis. Recently a second-generation CA 125 assay has been developed. The purpose of this study was to compare serum CA 125 concentrations in women with and without endometriosis using both the older assay and the new CA 125 assay and to determine if the new assay concentration improves the clinical utility of CA 125 in the diagnosis of endometriosis. A total of 123 patients with endometriosis, pelvic pain or infertility were enrolled. Blood for CA 125 was drawn in the cycle preceding laparoscopy or laparotomy, and concentrations found by the older and newer assays were correlated with the patients' endometriosis stage using the revised American Fertility Society classification of endometriosis. The CA 125 concentrations determined by the new assay were highly correlated with concentrations determined by the older assay in patients with and without endometriosis (r = 0.96). The sensitivity and specificity were slightly improved using the new CA 125 assay; however, this assay did not dramatically improve detection of endometriosis.