What Causes an Enlarged Uterus and How Is It Treated?

A number of common conditions can cause a uterus to stretch beyond its normal size.

Pregnancy

The uterus normally fits into the pelvis. When you’re pregnant, your growing baby will cause your uterus to increase in size 1,000 times, from the size of a clenched fist to a watermelon or larger by the time you deliver.

Fibroids

Fibroids are tumors that can grow inside and outside the uterus. Experts aren’t sure what causes them. Hormonal fluctuations or genetics may contribute to the development of these growths. According to the Office on Women’s Health at the U.S. Department of Health and Human Services, up to 80 percent of women have experienced fibroids by the time they turn 50.

Fibroids are rarely cancerous, but they can cause:

• heavy menstrual bleeding
• painful periods
• discomfort during sex
• lower back pain

Some fibroids are small and may not cause any noticeable symptoms.

Others can grow so large that they weigh several pounds and can enlarge the uterus to such an extent that you may look several months pregnant. For example, in a case report published in 2016, a woman with fibroids was found to have a uterus weighing 6 pounds. For comparison’s sake, the average uterus is about 6 ounces, which is roughly the weight of a hockey puck.

Adenomyosis

Adenomyosis is a condition in which the uterine lining, called the endometrium, grows into the uterine wall. The exact cause of the condition is unknown, but adenomyosis is tied to estrogen levels.

Most women see a resolution of their symptoms after menopause. That’s when the body stops producing estrogen and periods cease. The symptoms are similar to those of fibroids and include:

• heavy menstrual bleeding
• painful cramping
• pain with sex

Women may also notice tenderness and swelling in their lower abdomen. Women with adenomyosis can have a uterus that is double or triple its normal size.

Reproductive cancers

Cancers of the uterus, endometrium, and cervix can all produce tumors. Depending on the size of the tumors, your uterus can swell.

Additional symptoms include:

• abnormal vaginal bleeding, such as bleeding not related to your menstrual cycle
• pain with sex
• pelvic pain
• pain while urinating or feeling like you can’t empty your bladder

An enlarged uterus is usually found incidentally. For example, your doctor may identify an enlarged uterus during a routine pelvic exam as part of a well-woman checkup. It may also be identified if your doctor is treating you for other symptoms, like abnormal menstruation.

If your uterus in enlarged because of pregnancy, it will naturally begin to shrink after you deliver. By one week postpartum, your uterus will be reduced to half its size. By four weeks, it’s pretty much back to its original dimensions.

Other conditions causing an enlarged uterus could need medical intervention.

Fibroids

Fibroids that are large enough to stretch the uterus will probably need some kind of medical treatment.

Your doctor may prescribe birth control drugs, such as birth control pills that contain estrogen and progesterone or a progesterone-only device like an IUD. Birth control medication may halt the growth of the fibroids and limit menstrual bleeding.

Another treatment, known as uterine artery embolization,uses a thin tube inserted into the uterus to inject small particles into the arteries of the uterus. That cuts off the blood supply to the fibroids. Once the fibroids are deprived of blood, they will shrink and die.

In some cases, you may need surgery. Surgery to remove the fibroids is called a myomectomy. Depending on the size and location of the fibroids, this may be done with a laparoscope or through traditional surgery. A laparoscope is a thin surgical instrument with a camera on one end that’s inserted through a small incision or through traditional surgery.

Complete surgical removal of the uterus, called a hysterectomy, may also be advised. Fibroids are the No. 1 reason hysterectomies are performed. They’re generally done on women whose fibroids cause a lot of symptoms, or on women with fibroids who don’t want children or are near or past menopause.

A hysterectomy can be done laparoscopically, even on a very large uterus.

Adenomyosis

Anti-inflammatory medications, like ibuprofen (Advil, Motrin) and hormonal contraception such as the birth control pill can help relieve the pain and heavy bleeding associated with adenomyosis. These medications won’t help to decrease the size of an enlarged uterus, however. In severe cases, your doctor may recommend a hysterectomy.

Reproductive cancers

Like other cancers, cancers of the uterus and endometrium are typically treated with surgery, radiation, chemotherapy, or a combination of these treatments.

An enlarged uterus doesn’t produce any health complications, but the conditions that cause it can. For example, besides the pain and discomfort associated with fibroids, these uterine tumors can reduce fertility, and cause pregnancy and childbirth complications.

In one study published in Obstetrics and Gynecology Clinics of North America, fibroids are present in up to 10 percent of infertile women. Additionally, up to 40 percent of pregnant women with fibroids will experience pregnancy complications, such as requiring a cesarean delivery, having premature labor, or experiencing excessive bleeding problems postdelivery.

Many of the conditions that cause an enlarged uterus aren’t serious, but they can be uncomfortable and should be evaluated. See your gynecologist if you experience abnormal, excessive, or prolonged:

• vaginal bleeding
• cramping
• pelvic pain
• fullness or bloating in your lower abdomen

You should also contact your doctor if you have a frequent need to urinate or pain during sex. There are successful treatments, especially when conditions are caught early.