Endometrial hyperplasia is a condition that causes the uterine lining to become thicker due to an excess of the hormone estrogen without progesterone. It can cause irregular menstrual bleeding.

Cystic endometrial hyperplasia affects approximately 121 out of 100,000 people with uteruses per year.

This condition is not cancer. However, it can lead to cancer of the uterus in some cases.

This article focuses on endometrial hyperplasia without atypia, sometimes called cystic endometrial hyperplasia.

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Endometrial hyperplasia is a condition where the lining of the uterus (the endometrium) grows too thick. The condition is not cancer. However, it is precancerous as it can develop into cancer.

There are different types of endometrial hyperplasia. These are typically categorized based on cell changes in the lining of the uterus. These types are:

  • Endometrial hyperplasia without atypia: This type does not typically involve any irregular cells.
  • Atypical endometrial hyperplasia: A person with this type has irregular cells, and there is a higher risk of the condition developing into uterine cancer.

Doctors may also use the terms simple and complex to refer to the types of patterns within the cells.

Hyperplasia without atypia, also called cystic endometrial hyperplasia, is the most common and the most often benign (noncancerous) type of endometrial hyperplasia.

Learn more about endometrial thickness.

The most common symptom of endometrial hyperplasia is irregular uterine bleeding. This can include:

A person with endometrial hyperplasia may also have anemia due to excess bleeding.

Learn other causes of irregular periods.

The cause of endometrial hyperplasia is typically an excess of estrogen in the body.

During ovulation, the ovaries make estrogen, which causes the lining of the uterus to thicken. When one of the ovaries releases an egg, a person’s body begins producing progesterone to prepare it for pregnancy. If conception does not occur, the progesterone level drops, causing the uterus to shed its lining in the form of a period.

Endometrial hyperplasia occurs when a person’s body makes very little or no progesterone. A lack of progesterone means that the lining of the uterus does not shed, and instead gets thicker. The cells in the lining might then crowd together and become irregular.

There are many reasons that a person may have an imbalance of estrogen and progesterone. For example, if they:

When diagnosing endometrial hyperplasia, a doctor will ask a person about their symptoms and medical history before performing a physical examination and diagnostic tests.

A doctor will typically arrange an ultrasound scan to measure the lining of the uterus and to check for other causes of bleeding, such as ovarian cysts.

If the lining of the uterus is too thick, a doctor may recommend an endometrial biopsy. This involves removing some cells from the lining using a method that is similar to a Pap smear.

In some cases, a doctor may recommend a hysteroscopy. This is when a doctor inserts a thin camera and light into the uterus through the vagina. This allows them to see inside the person’s uterus to check for irregularities. A doctor may also take biopsies during this procedure.

A person can help reduce their risk of developing endometrial hyperplasia by taking certain steps, such as:

  • taking progesterone or progestin, a synthetic form of progesterone, if they are already taking estrogen
  • taking a birth control pill or other medication to regulate their menstrual cycle
  • quitting smoking, if applicable
  • reaching or maintaining a weight that is healthy for them

Doctors may recommend progestin therapy for people with endometrial hyperplasia without atypia.

A doctor may prescribe progestin in the form of:

A doctor may prescribe birth control pills containing estrogen and progestin to people who have not reached menopause. People who have reached menopause should not take these and should take birth control pills that are progestin-only.

A person will typically need to take progestin for at least 6 months. A doctor then will review the person’s symptoms and may perform a biopsy after 6 months to determine whether the treatment is working. A person will need at least two negative biopsies 6 months apart before no longer needing treatment.

Doctors do not typically recommend surgery for people with endometrial hyperplasia without atypia. This is because progestin therapy will often treat it effectively. However, a doctor may suggest a hysterectomy if:

  • the condition returns after treatment
  • progestin treatment is not working after 6–12 months
  • the condition develops into atypical hyperplasia

A person should contact their doctor if they experience:

  • periods that are heavier, last longer, or are more frequent than is typical for them
  • fewer than 21 days between each period
  • bleeding between periods
  • bleeding after menopause
  • having no periods before menopause
  • unusual vaginal discharge

Endometrial hyperplasia without atypia, or cystic endometrial hyperplasia, is a condition in which the lining of the uterus becomes too thick. It occurs when a person has an excess of estrogen without progesterone.

Doctors typically prescribe progesterone to help balance a person’s hormones and manage the hyperplasia.