Tests of Endometrial Receptivity
In any cycle (both natural and after egg collection in IVF), there is a window of opportunity where the endometrium (lining of the womb) is receptive and ready to receive an embryo. It is essential in treatment that embryos be transferred in treatment during this endometrial “window of implantation”. The timing of embryo transfer in IVF is conventionally based on a standard number of days following egg collection and on a standard number of days on progesterone medication.
The Endometrial Receptivity Array test (ERA) is a pioneering test that has been developed to evaluate the endometrial “receptivity” of a woman and may offer the opportunity to personalize the timing of embryo transfer to maximize chances of implantation.
A small sample from the womb lining on the day an embryo would normally be transferred and is analysed to assess the expression of 236 genes that are key to implantation and is abnormal in approximately 25% of couples with recurrent implantation failure. In these couples, a personalised embryo transfer is then planned to coincide with their individual “window of implantation” improving chances of success.
Initial studies (Ruis Alonso, 2013 Fertil Steril) and our Lister data does demonstrate an improved outcome in these couples and although no randomised top quality studies have yet been published to support this data, a randomized trial is currently in press whose preliminary data demonstrated a significant improvement in outcomes.
Further studies have also suggested that assessing for an imbalance in the natural endometrial biome (natural bacteria lining in the reproductive tract) or for chromic endometritis (inflammation or infection of lining of the womb) and treating may improve outcome. Again these lack randomised studies at present and are only performed in conjunction with ERA testing (as the ENDOMETRIO test) in those with recurrent failures of top quality embryos after discussion
There is currently no HFEA “traffic light rating” for treatments relating to endometrial receptivity. Read more about the HFEA traffic light system on fertility “add ons”.
A fertility “add-on” is an “optional extras that you may be offered on top of your normal fertility treatment, often at an additional cost. They’re typically emerging techniques that may have shown some promising results in initial studies but haven’t necessarily been proven to improve pregnancy or birth rates.”