Clinical management of endometrial receptivity

The endometrial window of implantation (WOI), the cycle days during which normal embryo implantation can occur, has generally been assumed to begin on cycle day 19 or 20 of an idealized 28 days cycle and last for 4 to 5 days. Noyes et al took the first steps in defining the WOI by establishing a set of morphological criteria to evaluate endometrial development and receptivity, but recent studies have invalidated their use in the routine evaluation of infertility. Based on greater than 10 years of extensive research, our group has developed a molecular diagnostic tool (the endometrial receptivity array [ERA] test) based on the specific transcriptomic signature that identifies the receptive endometrium in natural and artificial (hormonal replacement therapy) cycles. The ERA test has shown that some patients have a delayed WOI, others have an advanced WOI, and others can have unusually short windows of receptivity. This identification and characterization of the WOI allows the personalization of the embryo transfer. In this review, we describe the ERA and our experience with its use in assessment of the endometrial receptivity in patients undergoing assisted reproduction.