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Endometrial receptivity testing

For most patients, having a routine cycle of proven fertility treatment is effective without using any treatment add-ons.

Our ratings indicate whether the evidence from studies shows that a treatment add-on is effective at improving treatment outcomes for someone undergoing fertility treatment. Our ratings do not tell you how much that treatment add-on improves your chances of having a baby – please discuss this with your clinic.

What is endometrial receptivity testing?

Endometrial receptivity testing 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. Endometrial receptivity testing 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 are questions over whether the test is accurate at predicting the optimal window of implantation, and whether a patient has the same window of implantation for each of their cycles of treatment. If the test is inaccurate or the window of implantation varies for each cycle then the test may actually reduce the chances of having a baby.

Endometrial Receptivity Array (ERA) is a type of endometrial receptivity test.

Rated outcomes for endometrial receptivity testing
Rated red for increasing the chances of having a baby for most fertility patients
Red traffic light
For most fertility patients the use of endometrial receptivity testing is rated red because the findings from moderate/high quality evidence shows that this add-on may reduce treatment effectiveness.

Specific safety concerns about a treatment add-on, including those discussed above, are included under the dedicated section Is this treatment add-on safe?.

What do the ratings mean?

There are five ratings that indicate whether a treatment add-on is effective at improving treatment outcomes for someone undergoing fertility treatment, according to the evidence from studies. To make it easier to understand the scientific evidence for each treatment add-on we have a range of symbols and colours for each rated add-on below.

Green traffic light

On balance, findings from high quality evidence shows this add-on is effective at improving the treatment outcome.

Yellow traffic light

On balance, it is not clear whether this add-on is effective at improving the treatment outcome. This is because there is conflicting moderate/high quality evidence – in some studies the add-on has been found to be effective, but in other studies it has not.

Grey traffic light

We cannot rate the effectiveness of this add-on at improving the treatment outcome as there is insufficient moderate/high quality evidence.

Black traffic light

On balance, the findings from moderate/high quality evidence shows that this add-on has no effect on the treatment outcome.

Red traffic light

There are potential safety concerns and/or, on balance, findings from moderate/high quality evidence shows that this add-on may reduce treatment effectiveness.

All treatment add-ons on our list will have a rating to indicate whether the evidence shows that the treatment add-on is effective at improving the chances of having a baby for most fertility patients. Some treatment add-ons on our list may also have additional ratings for specific treatment outcomes. For example, whether the evidence shows that the treatment add-on reduces miscarriage. There may also be further ratings for specific patient groups, for example whether the evidence shows that the treatment add-on is effective for those who are aged over 40. Please see the individual webpages for each treatment add-on for their ratings.

An agreement between the HFEA and other professional and patient bodies (the 19th October 2023 consensus statement) stated that treatments that have no strong evidence of their safety and/or effectiveness should only be offered in a research setting. Patients should not be charged extra to take part in research, including clinical trials.

What’s the evidence for endometrial receptivity testing?

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.

At the October 2021 and July 2023 SCAAC meetings the Committee evaluated the evidence base for endometrial receptivity testing. Minutes of these discussions and the evidence used to inform them are available on the SCAAC webpage. The list of studies reviewed can be found under the section titled ‘Studies reviewed for this treatment add-on’.

Is this treatment add-on safe?

As this procedure requires obtaining a biopsy of the endometrium patients can experience cramping and there is a small risk of infection and bleeding. There is also a very small chance of uterine perforation. 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 requires patients to undergo a freeze-all cycle which carries a small risk that not all frozen embryos will survive the thawing process.

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

If you have any questions about the safety and risks, your clinic will be able to discuss whether a treatment add-on would be safe for you to use considering your specific medical history and circumstances.

Studies reviewed for this treatment add-on

The SCAAC have reviewed the following studies for Endometrial receptivity testing:

Simón 2020 10.1016/j.rbmo.2020.06.002
Cohen 2020 10.1080/19396368.2020.1824032
Cozzolino 2020 10.1007/s10815-020-01948-7
Cozzolino 2022 10.1016/j.fertnstert.2022.07.007
Doyle 2022 10.1001/jama.2022.20438

What are treatment add-ons?

In vitro fertilisation (IVF) and intrauterine insemination (IUI) are established treatments that have been proven effective for most patients. Treatment add-ons are optional non-essential treatments that may be offered in addition to such proven fertility treatment. Treatment add-ons are:

  • Additional treatments (to the core treatment e.g. IVF or IUI) that are being offered to the general patient population in licensed fertility clinics in the UK,
  • Where there is published scientific literature which claims to demonstrate that the add-on improves live birth rates or other treatment outcomes rated by the HFEA; but
  • where evidence of effectiveness for the use of the treatment in a clinical setting is lacking or absent; and
  • where patients need unbiased information about the effectiveness and risks of this treatment

It is important to keep in mind that for most patients, having routine cycles of proven fertility treatment are effective without using any treatment add-ons. If you are paying for your own treatment, you may want to think about whether it might be better to pay for multiple cycles of IVF or IUI, rather than spending large sums of money on a single treatment cycle with treatment add-ons that haven’t been proven to be effective.

We aim to publish clear and reliable information about some of the treatment add-ons that don’t have enough evidence to show that they improve your chances of having a baby and other relevant treatment outcomes. This provides useful information to patients and allows them to question the use of add-ons.

Review date: 19 October 2025