Endometrial hyperplasia is a precancerous condition in which there is an irregular thickening of the uterine lining. This may cause uncomfortable symptoms for women, including heavy menstrual periods, postmenopausal bleeding, and anemia due to the excess bleeding.  

Endometrial hyperplasia is most common among women in their 50s and 60s who have experienced menopause. It may also occur in women who are in perimenopause, a transitional state during which women still have their menstrual periods but on an irregular basis.  

Left untreated, endometrial hyperplasia may develop into endometrial cancer. Treatments are available to effectively manage the condition, which, in turn, helps to lower the risk that endometrial hyperplasia will advance to cancer.

“All women with changes in menstrual bleeding should be evaluated to see if they are at risk for endometrial hyperplasia. If they are, they can potentially be treated to reduce the chances of it progressing to endometrial cancer,” says Shefali Pathy, MD, MPH, a Yale Medicine obstetrician-gynecologist. 

During a woman’s childbearing years, her uterus develops a lining every month. If conception occurs, the uterine lining serves as a cushion for the fetus as it grows within the uterus. If conception does not occur, the uterine lining is shed through menstruation. Each month the cycle begins anew.

The root cause of endometrial hyperplasia is an imbalance between estrogen and progesterone; the condition may mean that the lining is not fully shed each month. When there is an unusual thickening of the uterine lining, it can result in what is known as endometrial hyperplasia. The condition is associated with heavy menstrual periods, short menstrual cycles (oligomenorrhea), and postmenopausal bleeding.

In women with endometrial hyperplasia, cells that amass in the uterine lining are abnormal and may, over time, become cancerous. For this reason, women with heavy periods and other symptoms of endometrial hyperplasia should not wait to seek diagnosis and treatment.

Endometrial hyperplasia develops when a woman has an imbalance of estrogen and progesterone. There are a number of reasons this can occur:

• Having irregular menstrual periods, being obese, or having polycystic ovary syndrome (PCOS) may interfere with ovulation, which reduces progestin exposure.
• During perimenopause, when a woman is not ovulating regularly, her exposure to progesterone is reduced.
• After menopause, a woman no longer ovulates, so she is no longer exposed to progesterone.
• The breast cancer medication tamoxifen mimics the effects of estrogen, without progestin (a synthetic chemical that mimics the effects of progesterone on the body). Some people take prescription estrogen without also taking progestin.

Women who have endometrial hyperplasia may experience:

• Heavier-than-normal menstrual periods
• Lengthier-than-normal menstrual periods
• Bleeding between menstrual periods
• Menstrual cycles that are shorter than 21 days
• Menstrual-type bleeding after menopause
• Anemia, in some instances, due to heavy menstrual bleeding

Women are more likely to develop endometrial hyperplasia after age 35, particularly if they:

• Started getting their menstrual periods at a young age
• Never became pregnant
• Were diagnosed with infertility
• Went through menopause at an older age
• Are obese
• Take tamoxifen, a breast cancer medication
• Take prescription estrogen without progesterone

Additionally, having these medical conditions may increase risk of endometrial hyperplasia:

• Diabetes
• Polycystic ovary syndrome (PCOS)
• Thyroid disease
• Gallbladder disease
• Lynch syndrome
• Cowden syndrome
• Being diagnosed with a tumor that excretes estrogen
• A personal or family history of uterine cancer, ovarian cancer, or colorectal cancer

Doctors are able to determine whether or not a woman has endometrial hyperplasia by learning about her medical history and symptoms, performing a physical exam, and offering diagnostic tests.  

During a medical history, doctors will ask about a woman’s history of irregular menstrual bleeding, as well as details about her menstrual history: When her menstrual periods began, when they ended (if applicable), how long her menstrual cycle is/was and whether she has ever been pregnant. The doctor should also ask about medication usage, specifically tamoxifen or estrogen.  

A pelvic exam may be normal, because endometrial hyperplasia doesn’t cause physical changes to the reproductive system.  

When a doctor suspects endometrial hyperplasia, they may recommend some additional tests.  A transvaginal ultrasound is an imaging tool that shows the inside of the uterus and allows doctors to see if the uterine lining is thicker than it should be.  

If the uterine lining is too thick, a biopsy of it will be offered to diagnose the condition. This can be done in the office in most cases. In some cases, however, a procedure, known as dilation and curettage (called a D&C) and hysteroscopy, can be performed with some sedation. In this procedure, a doctor inserts a hysteroscope—a tube equipped with a camera and a light—into the vagina, through the cervix, and into the uterus. This enables  the doctor to see inside the uterus. During the D&C portion of the procedure, the cervix is opened, or dilated, to allow the doctor to access the uterus. The doctor then uses a device called a curette to remove of the lining of the uterus. The results may show that the uterine lining cells are:

• normal
• abnormal yet non-cancerous
• abnormal and precancerous
• abnormal and cancerous

Abnormal findings that are non-cancerous and pre-cancerous indicate endometrial hyperplasia.

For women with endometrial hyperplasia who have abnormal, non-cancerous cells, progestin therapy may be recommended. This synthetic hormone helps to balance out the effects of estrogen in the system, which should eliminate or minimize symptoms of endometrial hyperplasia.

Women who have not yet reached menopause may be prescribed:

• Birth control pills containing progestin
• Birth control pills containing estrogen plus progestin
• Progestin injections
• Vaginal cream containing progestin
• An intrauterine device (IUD) that gradually releases a progestin (levonorgestrel)

Women who have reached menopause should not take birth control pills containing estrogen plus progestin. They may be prescribed:

• Progestin-only birth control pills
• Progestin injections
• Vaginal cream containing progestin
• An IUD that gradually releases progestin

For women with endometrial hyperplasia who have abnormal, pre-cancerous cells, hysterectomy may be recommended. This procedure removes the uterus, eliminating the possibility that endometrial cancer could develop. It’s important to note that having a hysterectomy means a woman is no longer able to get pregnant.

Treatment helps endometrial hyperplasia to resolve in most patients, so that women no longer experience heavy or abnormal menstrual bleeding. If endometrial hyperplasia is not diagnosed and treated, it may develop into endometrial cancer. For this reason, it’s important for women with symptoms of endometrial hyperplasia to seek treatment.

“Yale doctors are experts in evaluating abnormal bleeding and can effectively treat women with hyperplasia,” says Dr. Pathy. “Our team of gynecologists work with the patient to identify their goals and then develop treatment plans accordingly.”