Rated red by the HFEA for increasing the chances of having a baby for most fertility patients

What is endometrial receptivity array?

Endometrial receptivity array (ERA) is a test that claims to find the optimal time for an embryo to be transferred into a woman’s uterus for the embryo to implant, known as the window of implantation. ERA involves taking 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. The endometrium will be categorised as either receptive, pre-receptive, or post-receptive.

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. However, there is a question over whether a patient has the same window of implantation for each of their cycles of treatment.

ERA testing can be combined with 2 others tests called EMMA and ALICE. EMMA uses genetic testing of a sample of the lining of the womb to identify whether the types and percentages of bacteria present in this sample match those of successful pregnancies. If not, antibiotics and probiotics are sometimes suggested to balance these bacteria. ALICE looks at genetic analysis of a sample of the lining of the womb to detect bacteria causing chronic inflammation of the lining of the womb (chronic endometritis). These bacteria have been linked to infertility and pregnancy complications.

Risks of endometrial receptivity array

As this procedure requires obtaining a biopsy of the endometrium patients can experience cramping and there is a small risk of bleeding. It is not common for patients to have an infection after the biopsy but there is a small risk that if you have an infection within your cervix before the biopsy, this may cause the infection to spread into the uterus. Your clinic can treat this if necessary. The biopsy may need to be repeated in the rare event that either the results are inconclusive, or the biopsy fails to obtain a sufficient quantity or quality of tissue for testing.

Endometrial receptivity testing does not carry any additional known risks for the child born as a result of fertility treatment.

Evidence

Only one high quality randomised controlled trial (RCT) has been performed to study the effectiveness of endometrial receptivity testing at increasing a patient’s chances of having a baby. The outcomes of the study were promising but the results did not prove that endometrial receptivity testing made a difference to the patient’s chances of having a baby and we can’t be certain of their reliability. Another study, of a lower quality, has shown that the chances of having a baby were reduced with endometrial receptivity testing.

Aria’s view

There is conflicting evidence from studies on the effectiveness of ERA testing. However, a recent study analysed 2256 patients and found a significantly improved outcome in patients who underwent an ERA and had a subsequent personalised embryo transfer, compared to those who did not (Enciso et al, 2021).

We acknowledge that it is a new and growing field with limited evidence. We have therefore been offering this technique to selected patients, mainly those with repeated implantation failure despite transferring good quality embryos. Please see our separate patient information document “ERA EMMA and ALICE testing” for more detailed information.