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When good embryos keep failing to implant, the answer is often in the lining, not the embryo. Microbiome, immune, and receptivity testing from a single timed endometrial biopsy, interpreted personally, and only ordered when the result would change your treatment.
Home / Advanced Diagnostics / Endometrial Investigations
By Dr Vasileios Sarafis, MD, UK-trained fertility specialist. C.Re.A.Te Fertility, London. Last reviewed 25 May 2026
Most patients never need it. It earns its place in a specific group, where embryo quality and anatomy look right, yet implantation keeps failing. These are the situations where the lining itself is worth investigating.
/01
Repeated implantation failure despite good-quality embryos.
/02
Recurrent miscarriage or repeated biochemical pregnancies.
/03
Failed transfers where the embryos were graded well.
/04
Suspected chronic endometritis or persistent inflammation.
/05
A normal hormonal and anatomical workup that still has not explained the failures.
/06
Before a final transfer of precious or limited embryos, to leave nothing to chance.
Why the lining matters
“Implantation takes two: an embryo and an endometrium ready to receive it. When good embryos keep failing, it is worth asking whether the lining is inflamed, colonised by the wrong bacteria, or simply out of phase.”
For most women, the lining of the uterus does its job quietly and well, and no one needs to look any closer. This page is not for them. It is for the smaller group who have done everything right (good embryos, a normal-looking uterus, the correct protocol) and have still watched transfer after transfer fail.
When that happens, attention naturally falls on the embryo. But implantation takes two. A receptive endometrium has to be in the right phase, free of chronic inflammation, colonised by the right bacteria, and immunologically ready to accept a pregnancy. Each of those can go wrong quietly, invisibly on a scan, and each can be tested for.
Endometrial investigations read the lining directly from a single timed biopsy. They can reveal a microbiome dominated by the wrong organisms, a low-grade chronic endometritis, an immune environment that is rejecting rather than receiving, or a window of implantation that is simply mis-timed, and most of these, once found, can be treated.
I am deliberately conservative about ordering them. These tests have become a heavily marketed add-on, and run indiscriminately they cost a great deal and change very little. Run selectively, for the patient whose story points to the lining, they can be the thing that finally explains and fixes a run of failed cycles.
The endometrial testing in this practice is run by ATG (Access to Genome). You may have seen the branded panels — EMMA, ALICE and ERA are commercial products from a single company, Igenomix, often sold together as EndomeTRIO. I do not use them.
The reason is practical. Those panels are molecular only: they identify which organisms are present and suggest an antibiotic based on what usually works against that organism. The ATG panel adds conventional culture with antibiotic sensitivity testing alongside the sequencing, which measures how your own isolate actually responds to each antibiotic. Where the whole purpose of the test is to clear an infection before an embryo transfer, that is the difference between choosing the antibiotic from a table and choosing it from your result — and a failed first course of antibiotics costs a cycle.
Endometrial microbiome analysis is €400 and endometrial immunological testing €600. Every price is quoted to you in writing before anything is done.
The biopsy itself is a brief, in-clinic procedure, a thin pipelle sample taken at a precise point in your cycle. From that one sample, the labs can run any combination of three families of test, depending on your history.
I only order what is likely to change your plan, not a panel for its own sake. Results are interpreted personally and translated into a clear next step.
Microbiome
the bacterial balance & chronic endometritis.
Immune
the implantation-site immune response.
Receptivity
the timing of the window, where indicated.
Microbiome
Measures the balance of bacteria in the lining, specifically whether it is dominated by protective Lactobacillus or by organisms associated with poorer implantation. An imbalanced microbiome can often be corrected with targeted antibiotics or probiotics before the next transfer.
Infection
Chronic endometritis is a low-grade, often symptomless infection of the lining that is strongly linked to recurrent implantation failure and miscarriage. It is easily missed on standard tests and, once identified, is usually treatable with a targeted course of antibiotics.
Immune
Assesses the immune environment at the implantation site, including markers such as NK-cell activity and inflammatory balance. A disturbed profile in the context of recurrent loss or failure can point toward treatments that modulate the response in time for the next cycle.
Receptivity
Reads the genes the endometrium switches on as it becomes receptive, to check whether your window of implantation is on the standard schedule or shifted. If it is shifted, the transfer is re-timed to match. This is a personalised embryo transfer.
Histology
The sample is also examined directly for the cellular features of inflammation and other lining abnormalities, the conventional pathology that complements the molecular tests and confirms findings such as chronic endometritis.
Combined
For the right case, microbiome, infection, and receptivity testing can be run together from the one biopsy, a complete read of the lining in a single timed procedure, rather than repeated sampling across several cycles.
What’s included
The biopsy is performed in clinic by Dr Sarafis. The lab work is run by accredited specialist partners. The interpretation, the part that decides treatment, is done personally.
A timed in-clinic endometrial biopsy, performed personally by Dr Sarafis.
Cycle-timing guidance so the sample is taken at the correct point for the tests ordered.
Laboratory analysis by accredited specialist partners.
Only the tests that are clinically justified for your case, nothing run for its own sake.
Personal interpretation of the results in the context of your full history.
A clear written report with the findings and a specific, actionable treatment plan.
Consult
We review your history, previous cycles, and embryo quality together (€250) and decide whether endometrial testing is genuinely the right next step, and which tests, if any.
Quote
You receive a transparent, per-test quote covering the biopsy and only the justified lab tests. Nothing is ordered or charged until you have approved it.
Biopsy
A brief in-clinic biopsy is taken at the correct point in your cycle, performed personally, and sent to the accredited specialist labs.
Plan
A written report, the findings explained in plain English, and a specific plan: treat a microbiome imbalance or endometritis, modulate an immune response, or re-time the transfer, before your next cycle.
Pricing
Endometrial testing is priced per test, because the right combination differs from patient to patient. After your consultation you receive an itemised quote covering the biopsy procedure and only the lab tests that are clinically justified for your case. Nothing is run, and nothing is charged, until you have approved it. There are no hidden fees.
Competitive with UK & Western-European lab pricing · biopsy + interpretation included in the quote.
Start with a €250 online consultation. If testing is the right step, you get an itemised quote to approve before anything is run.
This is a careful, selective tool, not a routine add-on. Here is where it stops.
For a straightforward first or second cycle with no relevant history, the evidence does not support endometrial testing. Run indiscriminately it adds cost without changing outcomes. It is a selective tool.
These tests read the lining, not the embryo. Embryo quality, genetics, and sperm factors are separate questions answered by different investigations, The two are complementary, not interchangeable.
Finding nothing wrong with the lining is useful, it redirects attention elsewhere, but it does not on its own guarantee the next transfer will succeed. Implantation has many inputs.
Parts of this field, particularly some immune and receptivity testing, are still debated. I will tell you honestly where a test is well-established and where it is more exploratory, so you can decide with full information.
The approach
Endometrial testing has become a popular add-on, sold widely and often ordered for everyone. The evidence does not support that. For the right patient, repeated implantation failure, recurrent loss, a normal workup otherwise, it can find a treatable cause that nothing else explains. For most patients, it adds cost without changing the outcome.
My four years at C.Re.A.Te Fertility in London were spent on exactly these complex cases. I order these tests the way I learned to there, when the result will change what we do, and not before.
The principle
A test is only worth running if its result would change the plan. Everything else is just an invoice.
That is the filter every endometrial investigation here has to pass before it is ordered.
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Frequently asked questions
They are laboratory tests run on a small sample of the uterine lining (the endometrium), taken by a brief in-clinic biopsy at a precise point in your cycle. From one sample, the labs can assess the endometrial microbiome (the balance of bacteria), signs of chronic inflammation or infection, immune activity at the implantation site, and in selected cases the timing of the receptive window. They are used to look for treatable reasons that good embryos are not implanting.
A specific group: women with repeated implantation failure despite good-quality embryos, recurrent miscarriage or biochemical pregnancies, or an otherwise normal workup that has not explained why treatment keeps failing. For a first or second IVF cycle with no such history, these tests are usually not indicated and I will say so. They are a targeted tool, not a routine add-on.
The endometrium has its own bacterial community. When it is dominated by healthy Lactobacillus, implantation rates are better; when it is not, or when chronic infection (chronic endometritis) is present, implantation can fail repeatedly. Microbiome analysis measures that balance and screens for the bacteria most associated with chronic endometritis, so it can be treated with targeted antibiotics or probiotics before the next transfer.
At the moment of implantation, the lining has to strike a careful immune balance, tolerant enough to accept an embryo and active enough to support it. In some women with recurrent implantation failure or loss, that balance is disturbed, for example by an over-active NK-cell or inflammatory response. An immune profile from the biopsy assesses these markers and can point to treatments that modulate the response.
In selected cases, yes. A receptivity test reads the genes the endometrium switches on as it becomes receptive, to check whether your window of implantation is on the standard schedule or shifted. If it is shifted, the embryo transfer can be re-timed to match. It is most useful after repeated failures with good embryos and a lining that otherwise looks normal, not as a routine first-line test.
The biopsy uses a thin flexible catheter (a pipelle) passed through the cervix to collect a small sample. Most women describe a brief, sharp, period-like cramp lasting seconds, sometimes with mild cramping afterwards. It is done without sedation and takes only a few minutes. Taking simple pain relief beforehand, as advised, makes it more comfortable.
Pricing is per test, because the right combination depends on your history, so there is no single fixed price. After your consultation you receive an itemised quote covering the biopsy procedure and only the lab tests that are clinically justified for your case, and nothing is run or charged until you approve it. Pricing is kept competitive with UK and Western-European labs, with the biopsy and interpretation included in the quote.
No test can guarantee implantation. What these investigations can do is find and correct specific, treatable problems, an abnormal microbiome, chronic endometritis, a disturbed immune profile, or a mis-timed window, that may have been the reason previous transfers failed. Where a treatable cause is found and corrected, the odds improve. Where nothing is found, that is useful information too, and steers us elsewhere.
Start with an online consultation. We review your history together and decide whether endometrial testing is the right next step before anything is ordered.
