Prediction of endometriosis with serum and peritoneal fluid markers: a prospective controlled trial

BACKGROUND: The objective of this prospective controlled trial was to investigate the ability of a group of serum and peritoneal fluid (PF) markers to predict, non-surgically, endometriosis. METHODS AND RESULTS: Serum and PF samples were obtained from 130 women while undergoing laparoscopy for pain, infertility, tubal ligation or sterilization reversal. Concentrations of six cytokines [interleukin (IL)-1β, IL-6, IL-8, IL-12, IL-13 and tumour necrosis factor (TNF)-α] were measured in serum and PF, and reactive oxygen species (ROS) in PF, and levels were compared among women who were allocated to groups according to their post-surgical diagnosis. Fifty-six patients were diagnosed with endometriosis, eight with idiopathic infertility, 27 underwent tubal ligation or reanastomosis (control group) and 39 were excluded due to bloody PF. Only serum IL-6 and PF TNF-α could be used to discriminate between patients with and without endometriosis with a high degree of sensitivity and specificity (P < 0.001). A threshold of 15 pg/ml PF TNF-α provided 100% sensitivity and 89% specificity (positive likelihood ratio of 9.1 and negative likelihood ratio of 0). A threshold of 2 pg/ml for serum IL-6 provided a sensitivity of 90% and specificity of 67% (positive likelihood ratio of 2.7 and negative likelihood ratio of 0.14). CONCLUSIONS: By measuring serum IL-6 and PF TNF-α, it was possible to discriminate between patients with endometriosis and those without. Before these markers can be used as a non-surgical diagnostic tool, these data should be verified in a larger study.