Do endometriomas induce an inflammatory reaction in nearby follicles?

STUDY QUESTION: Do endometriomas induce an inflammatory reaction with increased cytokine concentrations in nearby follicles and thereby affect follicular development during controlled ovarian stimulation for in vitro fertilization (IVF)? SUMMARY ANSWER: With most endometriomas, there is no evidence of increased cytokine concentrations in the ipsilateral leading follicle. Infrequently, the concentration of inflammatory cytokines is increased in the follicular fluid (FF) and associated with diminished ovarian response. WHAT IS KNOWN ALREADY: The link between peritoneal endometriosis, inflammation and infertility is well established; however, the association between intraovarian inflammation and endometrioma is unknown. STUDY DESIGN, SIZE, DURATION: This prospective cohort study included 117 infertile women undergoing IVF in a tertiary infertility clinic at Oslo University Hospital Rikshospitalet, Norway, during the period May 2009 to September 2011. PARTICIPANTS, SETTING, METHODS: There were 47 patients with unilateral endometrioma and 17 patients with bilateral endometrioma, while the 53 control patients had unexplained or male factor infertility. Concentrations of IL-1 beta, IL-6, IL-8, IL-10, IL-12 and TNF-alpha were measured in serum and in the fluid of the largest pre-ovulatory follicles from each ovary of each participant. MAIN RESULTS AND THE ROLE OF CHANCE: Cytokine levels in the follicular fluid from the two ovaries in women with unilateral endometriomas were comparable, and were not significantly altered compared with that of control groups with male factor infertility, unexplained infertility or bilateral endometriomas. Compared with serum levels, the follicular fluid levels of IL-8 and IL-6 were higher, suggesting a local production or recruitment. The follicular fluid IL-8 level varied considerably and showed an inverse relationship with IL-12, IL-10 and TNF-proportional to, suggesting a complex interaction between various immune cells. A small group of patients (n = 3) had increased levels of all follicular fluid cytokines combined with moderately to slightly elevated serum levels and these patients had a significantly lower ovarian response. LIMITATIONS, REASONS FOR CAUTION: For ethical reasons, the endometriomas were diagnosed indirectly by ultrasound rather than by histology. WIDER IMPLICATIONS OF THE FINDINGS: This paper reveals that endometriomas seldom induce inflammation in nearby follicles during IVF; therefore, routine cystectomy prior to IVF may not be necessary. Cytokine levels in the follicular fluid, nonetheless, show distinctive patterns and increased levels may be linked to reduced ovarian response independent of the cause of infertility. STUDY FUNDING/COMPETING INTERESTS: The project was funded by the Norwegian Resource Centre for Women's Health, Oslo University Hospital. The authors have no conflicts of interests.