Interleukin-6 Concentration in Peritoneal Fluid and Serum of Patients with and without Endometriosis

Background:Endometriosis is a prevalent gynecological condition often diagnosed invasively through laparoscopy. The role of interleukin-6 (IL-6) in its pathogenesis suggests its potential as a non-surgical diagnostic marker. Objective: This study aimed to compare the levels of IL-6 in the peritoneal fluid and serum of patients with and without endometriosis, proposing IL-6 measurement as a non-invasive diagnostic approach. Patients and methods: This study was conducted at Ain Shams University Maternity Hospital from August 2008 to April 2010. This case-control study involved 80 patients undergoing laparoscopy for benign gynecological reasons. Group 1 included 40 patients with endometriosis, while group 2 consisted of 40 patients without pelvic pathology. IL-6 levels were measured using ELISA in both serum and peritoneal fluid collected during laparoscopy. Results: IL-6 concentrations were significantly higher in both serum (103.290 vs. 16.798) and peritoneal fluid (153.506 vs. 16.474) of endometriosis patients compared to controls (P < 0.05). A positive correlation (r=0.902) was found between serum and peritoneal IL-6 levels in the cases group, with significant differences in IL-6 levels across different stages of endometriosis. The optimal cutoff value for serum IL-6 was determined to be 25.4 pg/ml with a sensitivity and specificity reflective of its diagnostic potential. Conclusions: Serum and peritoneal fluid IL-6 levels were significantly elevated in endometriosis patients, correlating with disease severity. Serum IL-6, with a cutoff value of 25.4 pg/ml, could serve as a non-surgical diagnostic marker for endometriosis. Further validation in larger cohorts is recommended.