OBJECTIVE: Our purpose was to investigate the relationship between the levels of interleukin-6, interleukin-6 soluble receptor, and tumor necrosis factor-⍺ in peritoneal fluid and the size and number of active red endometriotic lesions.

STUDY DESIGN: In a university hospital 39 women of reproductive age underwent either laparoscopy for infertility workup or laparoscopic surgery for ovarian chocolate cysts. Peritoneal fluid was collected by laparoscopy. Active lesions, such as red flamelike lesions, glandlike lesions, and red vesicles, were scored according to the revised American Fertility Society classification system according to the size and number of active lesions. Peritoneal fluid levels of interleukin-6, interleukin-6 soluble receptor, and tumor necrosis factor-⍺ levels were determined by enzyme-linked immunosorbent assays. The relationship between peritoneal fluid concentrations of interleukin-6 and tumor necrosis factor-⍺ and the score of active endometriosis was investigated.

RESULTS: Peritoneal fluid levels of interleukin-6 and tumor necrosis factor-⍺ were significantly higher in patients with endometriosis compared with patients without endometriosis. The concentrations in patients with active endometriosis increased as the size and the number of active lesions increased. Cyclic variations in interleukin-6 concentrations were seen in peritoneal fluid from patients with endometriosis; the concentrations in the secretary phase were significantly higher than those in the proliferative phase.

CONCLUSIONS: Increased peritoneal fluid levels of interleukin-6 in patients with active red endometriosis may relate to endometriosis-associated infertility and to the pathogenesis of endometriosis.(Am J Obstet Gynecol 1997;176:593-7.)