The Correlation between Serum and Peritoneal Fluid CA125 Level in Women with Pelvic Endometriosis

Document Type : Original Article


1 Obstetrics and Gynecology Department, Infertility and Reproductive Health Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran

2 Immunology Department, Iran University of Medical Sciences, Tehran, Iran

3 Epidemiology and Reproductive Health Department, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran


Despite a high prevalence of endometriosis, there still exist many challenges in diagnosing the disease. This study aims to evaluate non-invasive and practical diagnostic methods by measuring serum and peritoneal fluid CA 125 levels in patients with endometriosis. A secondary aim is to determine the correlation between these markers with the stage of disease as well as the relationship of the two markers with each other.

Materials and methods
This is a cross-sectional study of 60 women who underwent laparoscopy for benign conditions. Based on laparoscopic findings and biopsy results, patients were divided to two groups; one group included patients with pelvic endometriosis (35 patients) and the second enrolled patients free from endometriosis (25 patients). Serum and peritoneal fluid specimens were provided at the time of laparoscopy and CA125 levels were then assessed by electrochemiluminescence immunoassay.

Mean serum and peritoneal fluid CA125 levels were significantly higher in women with endometriosis as compared to the control group (26.42 ± 24.34 IU/ml versus 12.64 ± 6.87 IU/ml in serum and 2203.54 + 993.19 IU/ml versus 1583.42 ± 912.51 IU/ml in peritoneal fluid, p <0.05). CA 125 levels also varied proportionally with the stage of endometriosis; but showed a significant difference only in higher stages of the disease, both in serum and peritoneal fluid. We calculated the cut-off value suggesting a diagnosis of pelvic endometriosis as 14.70 IU/ml for serum and 1286.5 IU/ml for peritoneal fluid CA125. A linear correlation between CA 125 levels in serum and peritoneal fluid in patients with pelvic endometriosis has also been observed.

Serum and peritoneal fluid CA 125 levels are simple and non-surgical tools for diagnosing and staging pelvic endometriosis. These markers are of greater diagnostic value in higher stages of the disease.