![]() ![]() Ideally, to ensure that the test detects (albeit very accurately) something that actually would be worth addressing, a non-selection study should be carried out. However, this only shows that the technology works as expected, not that its application results in any benefit to the patient. Several studies confirmed the technical correctness of the test by establishing that the result of an endometrial sample would always be the same (intra-biopsy reproducibility) and that this result would remain the same during the next cycle in which the embryo transfer would take place (inter-cycle reproducibility). (2) Unfortunately, while the idea is biologically plausible, the correct path for validation was not followed before marketing the final product. To this date, more than 150,000 ERA tests have been commercially performed. According to the manufacturer of the ERA test, 3 in 10 women suffer from a displaced window of implantation, which would make this the leading cause of infertility. This would be especially beneficial in patients with recurrent implantation failure (RIF), in which it would be even more likely for this window of implantation displacement to be the cause of the patient’s infertility. Therefore, a test that could first identify whether the endometrium was receptive at the “standard” time or not and then provide guidance on how much to adjust the transfer window for each particular patient would be extremely useful. Instead, the endometrium is 12-48 hours too early or too late in its transcriptomic profile, rendering the woman infertile and dooming all future transfers performed at the “standard” time to an ominous outcome. The premise of this test is that, in some women, the window of implantation is displaced, and the endometrium is thus not receptive at the time when the embryo is transferred. With the issue of embryo-endometrial synchrony being this important, it is no wonder that when the Endometrial Receptivity Array (ERA) test was released 10 years ago it was quickly adopted by reproductive medicine providers. On the question of whether it is the embryo, the endometrium, or the synchrony between the two that causes an embryo transfer to fail, the answer is likely “all of the above”. In the search for what causes the remaining one third of embryo transfers to fail, efforts have been focused on the main parameters that seem to contribute to a successful implantation and subsequent pregnancy: obtaining as many high quality euploid blastocysts as possible, and ensuring that the endometrium is receptive to sustained implantation. Recent research from IVIRMA has established that the likelihood of a euploid embryo transfer resulting in an ongoing pregnancy is approximately 65% (1). ![]()
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