O-165 Impact of endometriosis on the oocyte

Abstract Available evidence indicates that women with endometriosis tend to have lower implantation rates following IVF than those without endometriosis. Whether this reduction in implantation rate is due to compromised endometrial receptivity or reduced embryo quality remains controversial. However, studies with the oocyte donor model in which reciprocal transfers are performed involving oocytes/embryos from women with or without endometriosis support the conclusion that oocyte quality is the main factor compromising implantation rate. This conclusion is consistent with documented elevations of inflammatory cytokines, reactive oxygen species and growth- and angiogenic factors in follicular fluid and peritoneal fluid of women diagnosed with endometriosis. In this lecture, we will review evidence in support of negative effects of endometriosis on oocyte quality. We will discuss the results of studies directly assessing oocyte quality through gross morphological analyses and transmission electron microscopy assessments on human oocytes. Given the paucity of human oocytes available for research, we will then consider studies on animal oocytes matured in vitro in medium supplemented with either follicular fluid or peritoneal fluid from women with endometriosis. We will then proceed to reviewing the clinical IVF literature assessing the relationship between endometriosis and embryo quality, as the latter is predominantly driven by oocyte quality. We will specifically appraise studies investigating any association between endometriosis and 1) the proportion of good quality embryos and blastocyst formation rate, as categorized by conventional morphology assessment; and 2) risks of aneuploidy, and aberrations in embryo morphokinetics identified by time-lapse imaging. We will close by a brief discussion of the challenges that prevail in untangling negative effects of endometriosis on oocyte quality.