Equal amounts of research and consternation center on the proper cultivation, collection and treatment of oocytes during the IVF cycle. Only mature oocytes are a candidate for fertilization. Moreover, only a minor percentage of fertilized eggs will be candidate embryos for transfer. And now of these candidate embryos, a fraction of them harbor normal genetics and, when implanted, result in babies. The focus is on the oocyte-sperm, embryo unit.
However, the data is clear. Even the most normal of embryos (ones that have even tested to harbor normal chromosomes) have a an approximate 70% pregnancy rate (and a small miscarriage rate). We must now turn our attention to what can become the “rate-limiting step”, the bottleneck in implantation. It may rest in the endometrium.
Endometrial Receptivity Testing (ERA)
Endometrial Receptivity Testing (ERA) may be indicated as an assessment of the endometrium in women with repeated implantation failure. The window of embryo implantation is a mere 24 hours and in the majority of women occurs on the 5th day after ovulation (or in FET cycles the morning after the 5th dose of progesterone) Day 6. ERA testing allows for the assessment of the endometrial gene-expression signature. It is a validated test that will define the window of implantation. Testing results will verify if the window is correct or define if the course of progesterone should be either prolonged or decreased.