Abstract
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.
Keywords endometrial receptivity - implantation window - personalized medicine - embryo transfer
