Background: Implantation of an embryo in Artificial Reproductive Techniques is a complex process. With the advent of ERA, a diagnostic tool was supposedly developed to identify a receptive endometrium based on the array of 238 genes which are expressed at different times in a cycle.
Case: The current case describes a patient with three previously failed IVF cycles, who underwent an ERA testing in an HRT cycle, with diagnosis of a post receptive
endometrium. However, an embryo transfer was performed on day 5 after progesterone rise in a natural cycle, resulting in successful achievement of pregnancy, despite timing the embryo transfer outside the assumed window of implantation as diagnosed by ERA.
Conclusion: This puts into perspective the question whether ERA can be regarded as the ultimate tool of endometrial receptivity assessment.
1. A displaced window of implantation after an ERA in an HRT cycle may not be replicated in a natural cycle.
2. An accurately timed natural cycle, correlating ultrasound findings with hormonal profile is crucial for a successful embryo transfer.
3. Further large prospective studies are needed to confirm that a difference exists between an HRT and a natural cycle.