Failure of the embryo to implant now constitutes the major limiting step in IVF treatment. Successful implantation requires a vital embryo and an effective molecular dialogue with a 'receptive' endometrium. However, what precisely constitutes a receptive human endometrium remains poorly defined. Several observations have indicated that ovarian stimulation for IVF may impair endometrial receptivity. The histological approach to monitor endometrial maturation requires an invasive biopsy that excludes its use during the luteal phase of cycles in which implantation is the end-point objective as in IVF. In recent years, several studies have been reported that the removal of endometrial secretions immediately prior to embryo transfer provides sufficient material for analysis of markers of receptivity without disrupting embryo implantation. Therefore, analysis of protein patterns in endometrial secretion fluid may offer a relatively non-invasive means of assessing endometrial receptivity during fertility treatment cycles. Several studies have shown that protein profile expression in endometrial secretions undergo cyclical changes, and demonstrated significant differences between the natural cycle and stimulated cycle. These findings suggest that endometrial secretion analysis provide a novel means of investigating the effect of ovarian stimulation on the intrauterine environment at the time of embryo transfer, which may help to develop less disruptive ovarian stimulation protocols for IVF in the future.
Keywords: Ovarian stimulation; cytokine; endometrial receptivity; endometrial secretion; in vitro fertilization.