Endometrial Polyps

What are endometrial polyps?

Endometrial polyps, also called uterine polyps, are growths in the interior of the uterus (womb), formed of an overgrowth of the cells (endometrium) lining this cavity. They may occur alone or in clusters, and are typically smaller than a centimeter in diameter, but in rare cases can grow much larger – for example, to the size of a golf ball or an orange.

Symptoms in adults, both pre- and postmenopausal, commonly include unusual bleeding. Polyps are more common in people who have not yet experienced menopause than those who have. This may be because endometrial polyps seem to be reactive to estrogen levels. However, much is unknown about the formation of these polyps. They occur rarely among adolescents. Endometrial polyps can affect a woman’s fertility and, in rare cases, be linked to cancer.[1]

Uterine polyp symptoms

Common symptoms of endometrial polyps include:[2]

  • Irregular menstrual bleeding: Menstrual bleeding that is shorter or longer in length than usual, or that occurs at unexpected times
  • Spotting or bleeding between menstrual periods
  • Unusually heavy bleeding during periods
  • Unusual appearance of brown blood after a menstrual period
  • Spotting or bleeding after menopause
  • Spotting or bleeding after sexual intercourse
  • Severe menstrual cramping, though this is uncommon
  • Infertility

Many of these symptoms do not arise from the formation of the polyp itself, but instead because of rubbing and irritation of the surrounding tissue. Most endometrial polyps are small, and many people who experience them will never develop symptoms. Pain is not a typical symptom of uterine polyps.

Endometrial polyp causes

Endometrial polyps are caused by the overgrowth of endometrial tissue, which is the lining of the uterus that swells and then shrinks during the menstrual cycle. Endometrial polyps are estrogen-sensitive, with hormones in the bloodstream playing a role in their occurrence.[3][4]

Risk factors

Women older than 40 who have not experienced menopause, and those who have had children, are considered to be at greater risk of developing endometrial polyps. Other risk factors include:[5]

  • Going through perimenopause
  • Hormone replacement therapy after menopause, particularly where the dose of estrogen is high
  • Obesity
  • Treatment with the medication tamoxifen for breast cancer after menopause

Endometrial polyps may recur. People who have had polyps in the past are somewhat more likely to develop them in the future, compared to those who have never had them.

Diagnosis of endometrial polyps

Transvaginal ultrasound (TVUS) is the first-line method for evaluating women with abnormal vaginal bleeding. During a TVUS, a thin, wand-like device is placed inside of the vagina and uterus, where it emits ultrasonic waves. The doctor may be able to identify a uterine polyp by examining this ultrasound.

If the ultrasound finding is uncertain, there are two other options. One is where the physician carries out a more specialized ultrasound, called a sonohysterography or a saline infusion sonogram (SIS). In this procedure, the doctor injects a small amount of saline into the uterus to expand the uterine cavity and provide a clearer picture.

The second option, where a TVUS is uncertain, is a hysteroscopy. This allows a more direct view of the inside of the uterus using a hysteroscope: a lighted camera mounted on a flexible rod. The hysteroscope may be equipped with an additional tool to gather a biopsy sample. A suction catheter could also be used to gather an endometrial biopsy. The tissue sample will then be analyzed to see if it indicates uterine cancer.[6]


  1. Menstrual Disorders, Fibroids & Polyps.” The Center for Menstrual Disorders & Reproductive Choice. Accessed: July 18, 2017

  2. Uterine polyps.” Mayo Clinic. Accessed: July 18, 2017

  3. Uterine polyps.” Mayo Clinic. Accessed: July 18, 2017

  4. UpToDate. “Endometrial polyps.” August 29, 2017. Accessed April 6, 2018.

  5. Uterine polyps.” Mayo Clinic. Accessed: July 18, 2017

  6. Uterine polyps.” Mayo Clinic. Accessed: July 18, 2017