Why We Stopped Offering the ERA Test After 750+ Patients

Endometrial receptivity testing — sold as the ERA test — sets out to find the exact day your uterine lining is ready to accept an embryo. We used it in more than 750 patients at Jananam Fertility Centre, and we no longer offer it routinely.

This page explains what the test is, what it claims to do, what we found when we used it, and what we do instead for couples whose embryos keep failing to implant. It is written for patients who have been offered the test somewhere and want to understand it before agreeing.

On this page

• What endometrial receptivity means
• Three names for one test
• How the test is carried out
• Why it is an appealing idea
• What we found after 750+ patients
• What the wider evidence now shows
• What we do instead
• Questions worth asking about any add-on
• Common questions

What endometrial receptivity means

The endometrium is the lining of the uterus. Each month it thickens, and if pregnancy does not occur, it sheds as a period. For an embryo to implant, it has to arrive while that lining is in a receptive state.

That receptive state does not last the whole cycle. It is a short window, conventionally placed around days 19 to 21 of a natural cycle, and it is known as the window of implantation. The premise behind endometrial receptivity testing is that this window sits at a slightly different point in some women, and that finding it allows the transfer to be timed to the individual rather than to the standard day.

Three names for one test

The same test is sold under three names, and they mean the same thing: endometrial receptivity array, endometrial receptivity analysis, and endometrial receptivity assay. All three are shortened to ERA. If you have been quoted for one and read about another, they are not different tests.

How the test is carried out

It is not a blood test added to a visit you were already having. It requires a cycle of its own.

On day 2 of your period a scan confirms the lining is thin. Oestrogen is then given for around seven to twelve days until the lining reaches an adequate thickness, at which point progesterone is started — the same preparation used for a frozen embryo transfer.

At the point where an embryo would normally be transferred, a small sample of the lining is taken instead, using a fine catheter. Most women describe this as cramping similar to period pain rather than sharp pain. It is done in the clinic without general anaesthesia.

The sample is analysed for the activity of a panel of genes associated with receptivity, and the result reports whether the lining was receptive on the day tested. If it was not, the report indicates how far to shift the transfer.

Because the biopsy occupies the slot the transfer would have used, the transfer itself moves to a later cycle. In practice the test adds roughly a month, a procedure, and a bill.

Why it is an appealing idea

It is worth being honest about why this test sells as well as it does, because the appeal is genuine rather than manufactured.

Picture a couple who have transferred two or three good-quality embryos, all of which failed, and nobody has been able to tell them why. Endometrial receptivity testing offers a reason and a plan. For a clinician sitting opposite that couple, it is a very difficult thing not to offer.

That is also exactly why it warrants scrutiny. The group most drawn to an add-on is the group least able to weigh it, and a willingness to try anything is not evidence that something works.

What we found after 750+ patients

We offered endometrial receptivity testing for several years and used it in more than 750 patients. Over that period it did not produce an improvement in live birth rates large enough for us to continue recommending it.

We want to be precise about what that does and does not claim. It is not a finding that the test can never help any patient anywhere. It is a statement about what we observed across our own patients, in our own practice, and what we concluded from it.

What made the conclusion actionable was not the outcome by itself. It was the outcome set against the cost of getting there. When a test asks a patient for an additional cycle, an additional procedure and an additional bill, and does not return a matching improvement, continuing to offer it routinely becomes difficult to justify.

What the wider evidence now shows

The published evidence has since pointed the same way. An adequately powered, double-blind randomised trial found no significant advantage in live birth rates for receptivity-guided transfer compared with standard timing. Both ESHRE and ASRM now advise against routine use of endometrial receptivity testing outside research, including in women with repeated implantation failure.

The UK regulator rates treatment add-ons on a published traffic-light system — the HFEA’s assessment of endometrial receptivity testing is worth reading before agreeing to it anywhere. The ESHRE guidelines set out the same position for clinicians.

We mention this not to claim foresight. We reached our position from our own patients before that guidance settled. But a clinic’s own experience and the published literature arriving independently at the same place is a more reassuring picture than either on its own.

What we do instead

Withdrawing a test does not withdraw the problem. Couples with repeated implantation failure still need an answer, and a clinic that stops something owes them one.

For selected women with repeated implantation failure or recurrent pregnancy loss, we may assess the endometrial microbiome to identify potentially harmful bacteria. Immune testing is reserved for a specific subgroup rather than applied broadly; where it is indicated we may use endometrial immune profiling to guide treatment.

We also commonly consider preimplantation genetic testing for women aged 38 and above, or where there has been repeated IVF failure or pregnancy loss. Where the uterine cavity itself is in question, hysteroscopy looks at it directly rather than inferring it from a scan.

Where transfers have repeatedly failed, the assessment usually revisits the IVF cycle itself as well — stimulation, embryo quality and transfer technique — rather than treating the lining as the only variable. Repeated loss after implantation is a different problem again, and is set out on our page about recurrent miscarriage.

The word doing the work in all of that is selected. We offer add-ons selectively rather than routinely, and recommend one only where there is a reasonable clinical justification for that individual patient. How those decisions are made is set out separately.

Questions worth asking about any add-on

If endometrial receptivity testing — or any other add-on — is proposed to you, at this clinic or another, three questions are entirely reasonable to ask:

• What would the result change? If the plan is the same either way, the test is not earning its place.
• What evidence supports it, and what do the professional bodies say?
• What does it add in time, procedures and cost?

A clinic that cannot answer those three clearly is worth pressing on. We charged for this test for several years, which is part of why we think the question is worth putting plainly.

Common questions

What does an endometrial receptivity test actually measure?

It measures whether the lining of the uterus appears receptive to an embryo on the day the sample is taken, by analysing the activity of a panel of genes associated with receptivity. Receptivity conventionally falls around days 19 to 21 of the cycle, and the test checks whether yours matches that timing.

Does Jananam Fertility Centre offer the ERA test?

Not routinely. We used it in more than 750 patients and stopped, because in our experience it did not improve live birth rates enough to justify the additional cycle, biopsy and cost it required.

Is the biopsy painful?

Most women describe brief cramping similar to period pain rather than sharp pain. It is done in the clinic without general anaesthesia, and normal activity can usually be resumed the same day.

How much time does the test add to treatment?

Roughly a month. The biopsy is taken at the point in the cycle where an embryo transfer would otherwise happen, so the transfer itself moves to a subsequent cycle.

My embryos keep failing to implant. What should I do?

Ask for the whole picture to be reviewed rather than one test to be added. That usually means revisiting embryo quality and genetic status, looking directly at the uterine cavity where indicated, and considering whether anything in the stimulation or transfer itself should change. Both partners should be assessed.

Another clinic has recommended ERA to me. Should I have it?

That is a decision for you and the clinician who knows your history. What we would suggest is asking the three questions above, and reading the HFEA’s published rating of the test. Our position reflects what we observed in our own practice; it is not a statement about what is right for every patient everywhere.

Written and medically reviewed by Dr. Vani Sundarapandian, MD, DGO, FRCOG (UK) — founder and Medical Director, Jananam Fertility Centre, Chennai.