Interleukin-6 as A Useful Predictor of Endometriosis-Associated Infertility: A Systematic Review

Endometriosis is a chronic inflammatory disease defined by the presence of endometrial-like tissue outside theuterine cavity. Several authors have reported on the association between changes in inflammatory marker levelsand the maintenance or progression of endometriosis and associated infertility. Interleukin-6 (IL-6) is the moststudied cytokine in endometriosis and has important functions in reproductive physiology. The aim of this study isto review systematically available evidence about altered IL-6 concentrations in endometriosis-related infertility.This is a systematic review including all studies until December 2022 in which IL-6 in serum, peritoneal fluid,follicular fluid, or endometrial biopsy specimens was measured and that correlated their findings with endometriosis-associated infertility. Fifteen studies were included in the systematic review. There seems to be a correlationbetween elevated serum and peritoneal fluid IL-6 concentrations and the occurrence of endometriosis-associatedinfertility. IL-6 may be a potential diagnostic or biomarker tool for the prediction of endometriosis-related infertility.However, the numerous biases affecting the available studies, and challenges in endometriosis research reproducibilitymust be considered. Future investigations should pay attention to factors that may affect the results, suchas the choice of suitable control groups, and carefully consider other pathological conditions affecting the patients,endometriosis stage, and type of lesion.