Your pathology report for chronic endometritis

by Jason Wasserman MD PhD FRCPC
September 5, 2025

Chronic endometritis is a long-term inflammation of the endometrium, which is the inner lining of the uterus. Inflammation occurs when the immune system sends special cells to fight infection or injury. Unlike acute inflammation, which occurs suddenly and typically resolves quickly, chronic inflammation develops gradually and can persist for weeks or months.

Chronic endometritis may be associated with infection, but in some cases, no clear infection is found. This condition can affect reproductive health and has been linked to infertility and recurrent miscarriage.

What are the symptoms of chronic endometritis?

Some women with chronic endometritis have no symptoms, and the condition is only discovered during investigations for infertility or miscarriage.

When symptoms do occur, they may include:

  • Abnormal uterine bleeding, such as heavy periods or irregular bleeding.

  • Pelvic pain or a feeling of discomfort.

  • Unusual vaginal discharge.

  • Pain during intercourse.

  • Difficulty becoming pregnant.

  • Recurrent miscarriages.

If you experience any of these symptoms, it is important to speak with your doctor for further evaluation.

What causes chronic endometritis?

Chronic endometritis is often caused by a persistent infection in the uterus.

Common causes include:

  • Bacterial infections, such as Escherichia coli (E. coli) or Enterococcus.

  • Sexually transmitted infections, such as chlamydia or gonorrhea.

  • Tuberculosis, which is a very rare cause in some parts of the world.

Chronic endometritis may also develop after procedures involving the uterus, such as:

  • Dilation and curettage (D&C).

  • Placement of an intrauterine device (IUD).

In some women, no specific cause is identified.

How is the diagnosis made?

The diagnosis of chronic endometritis is made by combining medical history, symptoms, and laboratory tests. The most important test is an endometrial biopsy, where a small sample of tissue from the lining of the uterus is removed. A pathologist examines the biopsy under the microscope to look for features of long-term inflammation. In some cases, additional tests such as bacterial cultures, special stains, or molecular studies may be done to identify an infection.

What does chronic endometritis look like under the microscope?

When examined under the microscope, chronic endometritis shows several characteristic features:

  • Plasma cells: These immune cells are the most important feature of chronic endometritis. Their presence confirms long-term inflammation.

  • Lymphocytes and other immune cells: A mixture of different immune cells is often seen in the tissue.

  • Irregular glands: The normal glands of the endometrium may look distorted or irregular due to inflammation.

  • Fibrosis or scarring: In cases where inflammation has been present for a long time, scar tissue may develop, causing the lining to become thickened or fibrotic.

These findings allow the pathologist to confirm the diagnosis and rule out other conditions.

Why is chronic endometritis important?

Chronic endometritis is important because it may affect reproductive health. The ongoing inflammation can interfere with implantation of an embryo, making it harder to become pregnant. It is also linked to recurrent miscarriage. Fortunately, when an infection is identified, chronic endometritis often responds well to treatment with antibiotics.

Questions to ask your doctor

  • Was a specific infection identified as the cause of my chronic endometritis?

  • Do I need treatment with antibiotics or another therapy?

  • Could this condition explain my infertility or miscarriages?

  • Do I need follow-up testing after treatment?

  • Could my IUD or another procedure have contributed to this diagnosis?

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