Frozen embryo transfer: evidence-based markers for successful endometrial preparation.

Endometrial receptivity appears to be as important as chromosomal normality in determining embryo implantation and pregnancy outcome, because the ongoing pregnancy rate with transfer of preimplantation genetic testing for aneuploidy euploid blastocysts is ∼50%. This Views and Reviews article focuses on our current knowledge of the biology of endometrial receptivity and on the role of both invasive (endometrial biopsy) and noninvasive (ultrasound) assessment in successful endometrial preparation for frozen-thawed embryo transfer.