The ERA test – does it really work?

02 Nov The ERA test – does it really work?

The ERA test, or endometrial receptivity array test, is a new way to address implantation issues. But is it any good? A number of our fertility patients have had it. Some then had successful pregnancies, perhaps thanks to the ERA test’s recommendations. So let’s have a closer look.

The ERA test examines a sample of endometrial tissue to try to pinpoint the optimal moment for your embryo transfer. The makers of the test call this the ‘window of implantation’. The ERA test is primarily aimed at patients having fertility treatment. It’s quite expensive (around £850).

The ERA test claims to work out how receptive your endometrium is by assessing, at the genetic level, its readiness for implantation. If you’re a fertility patient with recurrent implantation failure, particularly after transferring good-quality embryos, it might be worth considering. The ERA test claims a 73% pregnancy rate.

What does the ERA test actually quantify? It measures the ‘receptive profile’ of your endometrium five days after starting your progesterone support. You’ll take HRT medication (estrogen and progesterone) up to your ERA test biopsy day – when a blastocyst (day 5) embryo transfer normally takes place. You’ll also need a monitoring scan around day 10, before you add in your progesterone.

You’ll get the written report a week or so after your ERA test biopsy. The key recommendation is the timing of your embryo transfer in relation to when, precisely, you start your progesterone. The advice might be: have your embryo transfer 126 hours, plus or minus three hours, after the start of your progesterone. So if you start your progesterone on your main cycle at 8 am, you should have your blastocyst transfer five days later, between 11 am and 5 pm, and ideally at 2 pm.

One thing your ERA test report might also say is that it’s only applicable on ‘the same type of cycle treatment’ on your main cycle as for the biopsy (mock) cycle. So if you’re having an FET, a donor-egg or donor-embryo cycle and are therefore on an HRT protocol, that’s okay. But what about IVF cycles using your own eggs? Not sure.

An ERA test can’t guarantee a future pregnancy. Other factors, such as poor embryo quality, blood disorders or immunology factors, can cause implantation failure. So it’s an objective, extra tool for guiding clinics towards greater success.

The key findings come from a 2013 study, which found that patients with repeat implantation failure are around 25% more likely to have a ‘displaced’ window of implantation. Hence why a personalised test that times your embryo transfer may help.

Another study in 2015 was also supportive. But a 2018 study found that, for FET patients, the ERA test didn’t seem to improve the pregnancy rate for good-prognosis patients. It concluded, like the 2015 study, that a large-scale trial was needed.

So should you have the ERA test? The best person to ask is your fertility doctor. It’s pricey. It’s uncomfortable. Our verdict? The ERA test’s genetic approach is certainly a step in the right direction. It may well improve outcomes for certain patients. But it’s not revolutionary – yet.