Endometrial Polyp: Understanding Your Pathology Report

Section Editor: Kianoosh Keyhanian MD FRCPC
September 2, 2026

An endometrial polyp is a noncancerous (benign) growth that projects from the lining of the uterus into the cavity of the uterus. The lining is called the endometrium. A polyp is made of the same two components as the normal lining: endometrial glands and supporting tissue. In a polyp, too many of these components are present in one place, and they are arranged differently.

Polyps may be attached by a narrow stalk or sit on a broad base. They range from a few millimeters to several centimeters, and a person may have one or several. They are common. Depending on the group studied and how they are looked for, polyps are found in somewhere between 8 and 35 percent of women, and they become more common with age.

Most endometrial polyps are benign. A small proportion contain precancerous changes or cancer, which is why they are examined carefully and usually removed. This article will help you understand what this diagnosis means on your pathology report, what each term means, and why it matters for your care.

What causes an endometrial polyp?

Polyps form when a small area of the lining grows more than the tissue around it. Estrogen drives the growth of the lining, so anything that increases estrogen exposure or reduces the balancing effect of progesterone makes a polyp more likely.

Age — The strongest factor. Polyps are most common in the years around menopause and remain common afterward.
Excess body weight — Fat tissue converts other hormones into estrogen, raising the amount reaching the lining.
Tamoxifen — A medication used in breast cancer treatment. It blocks estrogen in the breast but acts like estrogen in the uterus. Polyps in people taking it tend to be larger, more often multiple, and more likely to contain abnormal changes.
Hormone therapy — Menopausal hormone therapy makes polyps more likely to develop. It does not appear to make the polyps themselves more likely to be cancerous.
Other associations — High blood pressure, diabetes, and late menopause have all been linked with polyps, though the reasons are less clear.

Polyps are not caused by infection, are not contagious, and are not inherited in most cases.

What are the symptoms?

Many polyps cause no symptoms and are found incidentally during imaging or surgery for another reason. When symptoms occur, bleeding is by far the most common.

Bleeding between periods — Spotting or bleeding when a period is not expected.
Heavy or prolonged periods — Bleeding heavier or longer than usual for you.
Bleeding after menopause — Polyps are one of the more common causes. Any bleeding after menopause should be assessed promptly.
Difficulty becoming pregnant — Sometimes the reason the uterus is examined in the first place.

How is the diagnosis made?

A polyp is usually suspected before surgery. Ultrasound may show a focal thickening of the lining, and a saline infusion sonohysterogram, in which fluid is placed in the uterus during the scan, outlines a polyp more clearly. Hysteroscopy, in which a camera is passed into the uterus, allows the polyp to be seen directly and removed at the same time.

A pathologist makes the final diagnosis by examining the tissue under a microscope; how the tissue was obtained matters more than it might seem. An endometrial biopsy or a curettage performed without a camera samples the lining blindly, and a polyp can be missed entirely or come out in pieces. Reports often say fragments of endometrial polyp for this reason.

This matters because a fragmented polyp cannot always be assessed completely. Your doctor may recommend hysteroscopy so the polyp can be removed whole and examined in full. This applies if imaging shows a polyp but only fragments reach the laboratory, or if bleeding continues after a normal result.

What does an endometrial polyp look like under the microscope?

An endometrial polyp is a localized overgrowth of endometrial glands and supporting tissue projecting from the lining of the uterus. Pathologists rely on a combination of features rather than any single one.

Thick-walled blood vessels — Clusters of blood vessels with thickened walls sit within the core of the polyp. This is the most reliable feature and is not seen in normal lining.
Dense supporting tissue — The stroma within a polyp is firmer and more fibrous than the stroma of the surrounding lining.
Irregular glands — The endometrial glands within the polyp vary in size and shape, and many are dilated.
Glands out of step with the surrounding lining — The glands in a polyp often do not respond to hormones the way the rest of the lining does. A polyp may look inactive while the surrounding lining is growing, or vice versa.
Surface lining on more than one side — Because a polyp projects into the cavity, surface epithelium wraps around it rather than covering one side only.
Metaplasia — Areas where the lining cells take on a different but still normal appearance are common within polyps and are not precancerous.

What types of endometrial polyp are there?

Most polyps are reported as endometrial polyps. Some have features that earn a more specific name, which may appear in your report.

Endometrial polyp with gland crowding — The glands within the polyp sit closer together than usual. This is not the same as endometrial hyperplasia, which is a diagnosis about the lining as a whole. Your doctor may recommend sampling the lining outside the polyp to be sure hyperplasia is not present there.
Adenomyomatous polyp — Contains smooth muscle in addition to glands and supporting tissue. This is benign and is treated the same way as an ordinary polyp.
Atypical polypoid adenomyoma — A distinct and uncommon lesion, containing smooth muscle together with glands whose cells look abnormal. It is not an ordinary polyp, it can recur, and it needs closer follow-up. If your report uses this term, ask your doctor to explain what it means for you.
Mixed endometrial and endocervical polyp — Contains tissue from both the lining of the uterus and the canal of the cervix. This happens when a polyp arises near the junction of the two. An endocervical polyp is a separate, also benign, diagnosis.

Can cancer start in an endometrial polyp?

It can, but it is uncommon, and the risk varies widely depending on your situation. Pooled results from many studies give a useful picture.

Overall — Cancer is found in roughly 3 in 100 polyps removed.
Before menopause — About 1 in 100.
After menopause — About 5 in 100.
With bleeding — About 5 in 100, compared with about 2 in 100 in people with no symptoms.

Other factors that raise the likelihood include age over 60, a polyp larger than about 1.5 cm, tamoxifen use, excess body weight, high blood pressure, and diabetes. Precancerous change short of cancer, meaning atypical hyperplasia or endometrioid intraepithelial neoplasia, is found somewhat more often than cancer itself.

This is why the pathologist examines the whole polyp rather than a representative piece, and why polyps are usually removed rather than watched. If the pathologist finds cancer or a precancerous change, the report names it directly. A report that says endometrial polyp with no further qualification means the pathologist looked for those changes and did not find them.

How are endometrial polyps treated?

Removal through a hysteroscope, called hysteroscopic polypectomy, is the standard treatment. The camera lets the polyp be seen and removed completely, which relieves symptoms and provides the whole polyp for examination. Blind curettage is less reliable, because a polyp can be missed or only partly removed.

Not every polyp has to be removed. A small polyp causing no symptoms in someone before menopause may reasonably be watched. Up to a quarter of these resolve on their own within a year, particularly those under 1 cm. Removal is generally recommended when there is bleeding, when the polyp is large, or when you have gone through menopause. It is also recommended if you take tamoxifen or are trying to conceive.

Polyps can come back after removal, more often when several were present. Recurrent bleeding after a polypectomy is worth reporting rather than assuming the problem was dealt with.

Do endometrial polyps affect fertility?

They may. Polyps are found more often in people investigated for difficulty conceiving than in the general population. A polyp sitting in the cavity of the uterus may interfere with an embryo settling into the lining, or with sperm reaching the fallopian tube.

Removing a polyp before fertility treatment is commonly recommended, and studies of polypectomy before insemination or IVF have reported better pregnancy rates afterward. If you are planning fertility treatment and a polyp has been found, this is worth raising with your specialist.

What other findings may be described in the report?

Your report will describe the lining outside the polyp as well as the polyp itself, and that description matters as much as the diagnosis of the polyp.

The phase of the surrounding lining — Proliferative, secretory, or atrophic. This tells your doctor what the lining as a whole is doing.
Hyperplasia in the surrounding lining — If the lining outside the polyp shows crowded glands, that is reported separately and is managed on its own terms.
Chronic inflammation — If plasma cells are present, the report may add a diagnosis of chronic endometritis, which is associated with polyps.
Surface breakdown — Areas where the tip of the polyp has broken down and bled, often the direct explanation for the symptoms.
Whether the polyp is complete — The report may note whether the polyp was received whole or in fragments.

Questions to ask your doctor

Was the polyp removed completely, or only in fragments?
Did the polyp show any precancerous changes or cancer?
How large was the polyp, and was there more than one?
What did the report say about the lining outside the polyp?
Does my report use a specific type, such as adenomyomatous polyp or atypical polypoid adenomyoma?
Does this explain the bleeding I was having?
Should the lining be sampled again to check for hyperplasia?
Do I need a hysteroscopy to remove anything that was left behind?
I take tamoxifen. Does that change what you recommend?
How likely is a polyp to come back?
Could this be affecting my fertility?
Do I need any follow-up imaging or appointments?
What symptoms should prompt me to contact you?