Serum and peritoneal CA-125 levels as diagnostic test for endometriosis

Objective: To evaluate the clinical utility of CA-125 in the diagnosis of endometriosis and to compare the sensitivity of the serum and the peritoneal test as indicator of disease. Study design: Peritoneal fluid was obtained at laparoscopy. The quantitative determination of CA-125 in serum and in peritoneal fluid was performed by IRMA-mat CA-125 'two-step method', a two-site immunoradiometric assay, using 35 and 60 U/ml as cutoff. Setting: Second Department of Gynecology and Obstetrics, Second University of Naples, Italy. Participants: A total of 26 women infertile undergoing diagnostic laparoscopy that exhibited endometriosis in 14 patients, normal pelvis in 12 patients (control group). Interventions: None. Results: CA-125 levels in peritoneal fluid were higher than those found in serum and were significantly elevated (P < 0.05), when compared with the control group, both in women with endometriosis stage I-II and stage III-IV. In serum, CA-125 levels increased only in advanced stage of endometriosis. Conclusions: Levels of CA-125 in peritoneal fluid seem to be a more sensitive indicator of disease than serum levels (0.86 vs. 0.36), especially in early stage endometriosis (0.80 vs. 0.20) which tends to be overlooked by the CA-125 serum test.