Endometrial Receptivity Array

The Endometrial Receptivity Array (ERA) is a procedure that is used to diagnose if the endometrial cavity is ready for embryo implantation.

Endometrial Receptivity Array (ERA)

The Endometrial Receptivity Array is a diagnostic procedure that helps to find the optimal time for an embryo to be transferred into a woman's uterus for implantation. ERA involves the taking of a biopsy of the endometrial lining of the uterus and testing the tissue to see which genes are expressed. When combined with a computational predictor these results indicate when the endometrium may be most receptive to an embryo implanting. Problems with the endometrial lining are one of the causes for infertility in women with recurrent pregnancy loss or multiple failed in vitro fertilisation (IVF) transfers.

Window of Implantation

A woman's uterus is usually most receptive to an embryo around days 19-21 of the menstrual cycle, which is when embryo transfer is typically carried out.

This period is known as the "window of implantation". But in some women, this window may in fact be earlier or later, and this may lead to the failure of IVF. ERA is a test that allows us to assess whether or not the uterus is receptive at the usual time. Based on the results of the test, we can alter the time of embryo transfer, in the hope of increasing the chance of an embryo implanting successfully.

How is it done?

A biopsy is to be done to obtain a small amount of tissue for testing. Before this sample is taken, the patient is given progesterone supplements for 5 days. Some women experience cramping or light bleeding during or after the procedure. The sample is obtained and sent to a lab where molecular analysis is completed to determine the best time to attempt embryo implantation in a future IVF cycle. There are over 238 genes that must be assessed through this test.

There are three potential results

  • Pre-receptive. The lining is not yet ready to receive an embryo, and implantation is less likely to occur.
  • Receptive. The lining is ready to receive the embryo, which is most likely to implant.
  • Post-receptive. The lining has already reached the stage for optimal embryo implantation but is no longer in that stage. The embryo is less likely to implant at this time.

The endometrial receptivity assay (ERA) attempts to analyse the endometrial lining at the molecular level, and elicits further information about this window of implantation. In subsequent cycles of treatment, the patient will then have what is termed a 'personalised embryo transfer', taking place at the optimal time for her specific window of implantation. This would theoretically increase the chances of the embryo implanting successfully and the patient having a baby.