Embryotoxicity of Peritoneal Fluid in Women with Endometriosis. Its Relation with Cytokines and Lymphocyte Populations

Background: The goals of the present work were to study the embryotoxic effects of peritoneal fluid (PF) in women with or without endometriosis, and to relate any embryotoxicity to the severity of endometriosis, infertility or achievement of pregnancy, cytokine concentrations and lymphocyte populations.

Methods: Sixty-six consecutive women of reproductive age, 54 with endometriosis (21 infertile) and 12 infertile without endometriosis, and another 12 fertile women as control group, were included in this study. They all underwent laparoscopy or laparotomy in the second half of the cycle, and PF was collected from the pouch of Douglas. The embryotoxicity of the PF was assessed by means of a mouse embryo assay, and expressed as the number of embryos that did not reach blastocyst stage. Cytokines and lymphocyte populations present in PF were also studied and correlated with embryotoxicity.

Results: PF embryotoxicity was increased in women with endometriosis, but there was little correlation with the severity of the disease. However, although a clear relationship to the presence of infertility was not found, embryotoxicity appeared to be lower in those infertile patients with endometriosis who later became pregnant. We found a significant increase in embryotoxicity in the presence of high cytokine concentrations, especially with interleukin-6, and less so with interleukin-8 (P < 0.05). No good correlation was observed with lymphocyte populations, but CD56 (NK) cells were significantly increased in the PF of women with endometriosis. In general, the correlations for embryotoxicity were better when PF was diluted at 20% (91.4 +/- 17 versus 68.1 +/- 31, P < 0.01).

Conclusions: These results suggest that alteration in the production of cytokines in the PF, especially IL-6, besides contributing to the endometriosis and its evolution, probably increases embryotoxicity. However, no correlation was found between the latter and associated infertility.