ENDOMETRIAL RECEPTIVITY ANALYSIS
Endometrial receptivity is the most crucial parameter for successful implantation in an IVF procedure. Understanding a person’s individualized receptive endometrial window is very difficult to work but at the same time, it is most important to catch the window of implantation to give a successful pregnancy in an IVF cycle. The window of implantation is not the same for all women; rather it is individualized and is displaced in one in four patients and it is the reason for most of the recurrent implantation failures.
Endometrial receptivity array testing is a diagnostic molecular tool that is based on the endometrial gene expression to find a woman’s individualized window of implantation. It gives the assessment of the gene expression of a particular endometrial sample and compares the different 236 genes expressed in a receptive endometrium and it gives the result as receptive or non-receptive endometrium.
Indication of ERA testing
- recurrent implantation failure where there is a failure of more than 3 to 4 IVF cycles despite giving morphologically good quality embryos.
- Before transferring PGS embryos.
The implantation window of the human embryo occurs 6 to 10 days post ovulation. It lasts approximately four days from 20 To 24 of a regular menstrual cycle.
Endometrial Preparation And Biopsy Timing
It can be performed in a natural cycle, modified natural cycle, or a hormone replacement therapy protocol.
In a natural cycle, the endometrial biopsy is performed at LH surge for seven days.
In a modified natural cycle, HCG injection is administered when the follicle size becomes more than 17 mm, and the biopsy is taken after seven days.
In an HRT protocol, the endometrial preparation is done by serial administration of estrogen tablets and when the endometrium reaches more than 6to 7 mm, progesterone administration starts and the biopsy is performed 6 a day of progesterone support.
Interpretation Of Results
The result can be receptive or non-receptive.
Receptive means that the gene expression is similar to a normal receptive endometrium and the actual embryo transfer is performed in a similar way the ERA has been done.
Non-receptive can be pre receptive or post-receptive. Then the actual embryo transfer should be performed at the given time according to the result.
Clinical outcome after ERA
ERA gives the best time to transfer embryos, hence the implantation rates increase. It allows individualized embryo transfer and clinical outcome improves. It also helps to improve the ongoing pregnancy rates compared with fresh embryo transfer.