- Test explainer · reviewed by Dr Sarafis
Chronic endometritis
Of everything that can quietly undermine implantation, chronic endometritis is the one most likely to be missed by standard testing, and the one most reliably treated once it is found.
By Dr Vasileios Sarafis MD. UK-trained fertility specialist, Thessaloniki and Athens. Last reviewed 12 June 2026.
- Endometritis
- Chronic endometritis
- Strongest evidence
Chronic endometritis is a low-grade, often symptom-free inflammation of the endometrial lining, driven by certain bacteria. It rarely causes obvious symptoms, which is exactly why it is missed. And of all the findings in recurrent implantation failure, it is among the most reliably treatable once it is identified.
What the test looks for
Molecular testing for chronic endometritis looks specifically for the pathogens most often responsible for chronic endometritis: certain streptococci, enterococci, gardnerella, mycoplasma, and ureaplasma. It is performed on an endometrial biopsy, typically the same single sample used for microbiome analysis.
Chronic endometritis can also be identified at hysteroscopy and on histology, where plasma cells in the endometrial tissue are the hallmark. ALICE adds the ability to name the specific organisms involved, which guides the choice of antibiotic.
This is one of the more encouraging findings in the field.
Several meta-analyses report that successfully clearing chronic endometritis is associated with markedly higher ongoing pregnancy and live birth rates, with treated patients reaching outcomes comparable to women who never had the condition. The evidence is not unanimous, and at least one analysis found no clear benefit from oral antibiotics, with the benefit appearing strongest in higher-grade disease treated with an adequate course. On balance it remains the finding in recurrent implantation failure that is most reliably acted upon when it is present.
Why it gets missed
Chronic endometritis usually produces no symptoms a patient would notice. It does not reliably show up on a routine pelvic scan. Unless someone specifically looks for it, through hysteroscopy, histology, or molecular testing, it goes undiagnosed. A patient can go through several failed transfers with a treatable, silent infection that nobody tested for.
How it is treated
Treatment is usually a targeted course of oral antibiotics, chosen based on the organisms identified, often followed by probiotic restoration. Where appropriate, a test of cure confirms the infection has cleared before the next transfer is planned. It is one of the few situations in this field where a specific, treatable cause can be found and addressed directly.
Key takeaways
- Chronic endometritis is a silent, low-grade infection of the endometrial lining.
- Molecular testing identifies the specific pathogens responsible, guiding antibiotic choice.
- It is the diagnosis most likely to be missed by standard testing.
- Once identified, it is among the most reliably treatable findings in recurrent implantation failure.
When I recommend it
Because chronic endometritis is common, silent, treatable, and well evidenced, testing for it is one of the investigations I most often recommend in recurrent implantation failure. This assessment should also include what to review after a failed embryo transfer. It is usually run together with the endometrial microbiome and the EMMA test on a single biopsy, so a complete picture of the endometrial environment comes from one procedure.
What about ALICE, EMMA and EndomeTRIO?
You will meet these names on clinic websites and in patient forums. ALICE (Analysis of Infectious Chronic Endometritis), EMMA (Endometrial Microbiome Metagenomic Analysis) and ERA (Endometrial Receptivity Analysis) are commercial products from one company, Igenomix, frequently sold together as the EndomeTRIO panel. They are brand names, not the names of the underlying tests.
Chronic endometritis can be identified by molecular testing of an endometrial biopsy, by histology using CD138 immunostaining, and at hysteroscopy. Several laboratories offer these and the clinical question is the same. I do not use the Igenomix panels. The endometrial testing in my practice is run by ATG (Access to Genome), and it adds something the molecular-only panels do not: conventional culture with antibiotic sensitivity testing alongside the sequencing. That matters here more than anywhere else in fertility testing, because the whole point of diagnosing chronic endometritis is to treat it. A molecular panel identifies the organism and suggests an antibiotic based on typical susceptibility; culture with sensitivities shows how your own isolate responds to each one. It is the difference between an educated guess and a measured answer — and it matters because a failed first course of antibiotics costs you a cycle.
If another clinic quotes you a branded panel, ask three things: what exactly does it measure, which laboratory performs it, and what would change in my treatment depending on the result.
- Where to go next
It is run alongside endometrial microbiome analysis as part of a coordinated endometrial workup, with hysteroscopy added where the ultrasound or history points to it.
What is chronic endometritis?
Chronic endometritis is a low-grade, often symptom-free inflammation of the endometrial lining caused by certain bacterial pathogens. It is associated with reduced implantation rates and recurrent pregnancy loss, and it frequently goes undiagnosed because it produces no obvious symptoms.
What is the ALICE test?
Molecular testing for chronic endometritis is performed on an endometrial biopsy and identifies the specific bacterial pathogens linked to chronic endometritis, such as certain streptococci, enterococci, gardnerella, mycoplasma and ureaplasma. Naming the organism guides the choice of antibiotic.
Does treating chronic endometritis improve pregnancy rates?
The evidence is encouraging though not unanimous. Several meta-analyses show that clearing chronic endometritis is associated with markedly higher ongoing pregnancy and live birth rates, with treated patients reaching outcomes similar to women who never had it, while some studies have found a less clear effect. It is the finding in recurrent implantation failure most reliably acted upon when present.
Common questions.
- Frequently Asked Questions
- Book your endometrial workup
Rule out the most treatable cause first.
Chronic endometritis is common, silent, and treatable. Endometritis testing and endometrial microbiome analysis are performed on a single biopsy and interpreted alongside your full history. The first step for most international patients is to book an online consultation for a detailed case review.
Sarafis Fertility Clinic · Thessaloniki & Athens · info@sarafisfertility.com · +30 210 444 9027
This page is for educational purposes and does not constitute medical advice. Indications for recurrent implantation failure investigation depend on individual clinical history and prior treatment. For guidance specific to your situation, book a consultation.