Improving pregnancy rates have been the focus of fertility centers since 1978 after the birth of Louise Brown, the first child conceived after IVF cycle treatment. Since then, laboratory advances have improved remarkably and the implantation rates for IVF has increased significantly. Still, the delivery rate may be lower in certain patients. Pre-implantation genetic screening of embryos heralded a new development that allowed even greater success with implantation, and pushed the consideration for single embryo transfers (SET) to limit the risk of multiple pregnancies. Still, patients and physicians remain frustrated by continued unsuccessful attempts despite multiple transfers of euploid embryos identified by a-CGH or embryos derived from young, presumably normal, egg donors. It is very challenging to explain why patients don’t conceive in circumstances where the endometrial cavity appears normal and the endometrium development seems prepared by commonly realized ultrasound parameters,. Although we realize that not all euploid embryos or embryos from egg donors will implant, after several transfers without success, we try to provide an explanation to patients about else could impede the implantation of these embryos.
There is now a new method to get more information about the uterine environment at the time of embryo transfer. The Endometrial Receptivity Array (ERA) examines the endometrium at the molecular level by evaluating 238 genes expressed within the endometrium during the implantation window. These genes are expressed within normal endometrium that is prepared to support implantation of an embryo. Several recent studies support using the test as many show that > 75% of the patients with repeated failed implantations of good quality embryos have a lining that was not receptive for implantation. Importantly, the results of the biopsy helps to guide the correct timing for transfer by adding or reducing the number of days of progesterone support to create a lining that is receptive for implantation. These data confirm a significant improvement in pregnancy rates in those patients after adjusting the timing of progesterone supplementation based on the results of the assay.
The endometrial biopsy for the ERA test is performed in just a few minutes in the office. The material is sent for evaluation and takes approximately 7 – 10 days to analyze. This allows changing only the number of days of progesterone support before transfer and all other medications used with the frozen transfer cycle remain the same. This new test and protocol adjustment provides a new opportunity for improving ongoing clinical pregnancy rates in many women who have suffered from repeated failures with high-quality embryos.