Chronic Endometritis: The Quiet Implantation Blocker

What is chronic endometritis?

Chronic endometritis is a persistent, low-grade inflammation of the endometrium, the lining of the uterus. Unlike a sudden pelvic infection, it tends to smolder quietly, often producing no clear symptoms at all.

When symptoms do appear, they can be vague: light spotting between periods, mild pelvic discomfort, or unusual discharge. The inflammation is thought to disturb the lining's ability to accept an embryo, which is why it draws attention in fertility care. According to the American Society for Reproductive Medicine, assessing the uterine cavity and lining is a standard part of evaluating female infertility 1Ref 1Practice Committee of the American Society for Reproductive Medicine (2021).Fertility evaluation of infertile women: a committee opinion.ASRM committee opinion establishing that assessing the uterine cavity and lining is a standard part of the female fertility evaluation.. Estimates of how often it occurs range widely because studies define it differently.

How is chronic endometritis diagnosed?

Diagnosis rests on a sample of the uterine lining rather than symptoms, since the condition is usually silent. A clinician takes a small endometrial biopsy, and a pathologist looks for plasma cells, a type of immune cell, often using a special stain called CD138.

Hysteroscopy can add clues, such as a reddened or swollen lining. There is no single agreed threshold for how many plasma cells define the condition, which is one reason estimates of how common it is vary so widely between studies. Because infertility affects roughly 1 in 6 people of reproductive age according to the World Health Organization, clinicians reserve this testing for situations where it is most likely to change the plan 2Ref 2World Health Organization (2025).Infertility (fact sheet).WHO fact sheet states about 1 in 6 people of reproductive age experience infertility, used to explain why lining biopsy is reserved for higher-yield situations.. A biopsy is a brief office procedure that usually needs no anesthesia.

How is chronic endometritis linked to implantation failure?

Chronic inflammation appears to make the lining less receptive, so a healthy embryo is less likely to implant and stay. The altered immune environment may also raise the chance of early loss, though the research is still maturing and findings are mixed.

This is why testing tends to follow a pattern of disappointment: repeated failed embryo transfers or recurrent miscarriage. Miscarriage is common on its own, affecting about 10% of recognized pregnancies according to the American College of Obstetricians and Gynecologists, so clinicians weigh whether inflammation is truly the culprit 3Ref 3American College of Obstetricians and Gynecologists (2018).ACOG Practice Bulletin No. 200: Early Pregnancy Loss.ACOG Practice Bulletin No. 200 states early pregnancy loss occurs in about 10% of recognized pregnancies, context for weighing whether inflammation is the cause.. Reviewing the timeline of failed embryo transfers helps decide whether a biopsy is worthwhile. The link is clearest in people with several failed transfers rather than a single one.

How is chronic endometritis treated?

Treatment is usually a course of oral antibiotics aimed at clearing the underlying inflammation. Many clinicians repeat the biopsy afterward to confirm the plasma cells are gone before another transfer.

Whether treating chronic endometritis reliably improves pregnancy rates is still debated, because high-quality trials are limited and definitions differ. Some studies suggest better outcomes after successful treatment, while others show little difference. Guideline groups therefore frame it as a reasonable step in selected cases rather than a routine test for everyone. Ruling out coexisting problems, such as uterine scarring, is part of the same careful workup. If a repeat biopsy still shows inflammation, a clinician may adjust the approach before another attempt.

When chronic endometritis needs testing

A reproductive endocrinologist is best placed to decide whether a lining biopsy belongs in your workup. Testing tends to make the most sense after two or more failed embryo transfers or repeated pregnancy losses, rather than at the very start of trying; expert guidance on recurrent pregnancy loss supports evaluating the uterine environment in these cases 1Ref 1Practice Committee of the American Society for Reproductive Medicine (2021).Fertility evaluation of infertile women: a committee opinion.ASRM committee opinion establishing that assessing the uterine cavity and lining is a standard part of the female fertility evaluation.4Ref 4Practice Committee of the American Society for Reproductive Medicine (2026).Recurrent pregnancy loss: a committee opinion.ASRM committee opinion on recurrent pregnancy loss supporting evaluation of the uterine cavity and environment after repeated losses or failed transfers.. In practice this often follows 12 months of trying, or 6 months if you are over 35, without success 1Ref 1Practice Committee of the American Society for Reproductive Medicine (2021).Fertility evaluation of infertile women: a committee opinion.ASRM committee opinion establishing that assessing the uterine cavity and lining is a standard part of the female fertility evaluation.. Chronic endometritis is a concern of the reproductive years, when implantation matters most; it is rarely relevant in adolescence and fades from the picture after menopause. Because the evidence is still evolving, decisions are individualized and weighed against other findings. Gale can help you prepare for that conversation.