From conception to delivery, your uterus can grow from the size of a pear to the size of a watermelon. But pregnancy isn't the only possible reason for an enlarged uterus. An enlarged uterus is common and can be a symptom of several medical conditions, some of which require treatment.
Two of the most common causes of an enlarged uterus are uterine fibroids and adenomyosis.
Uterine fibroids are common noncancerous tumors of the muscular wall of the uterus, affecting as many as 8 in 10 women by age 50. They most often affect women over 30, and are more common in Black people than in White people. If you're overweight or have obesity, you're at greater risk of fibroids. Genetics and hormones contribute to their growth.
While some fibroids are very small, others grow to weigh several pounds. You can have a single fibroid or many. In addition to an enlarged uterus, symptoms of fibroids may include:
Your doctor may recommend various types of medications or an intrauterine device (IUD) to help control pain or heavy periods. Or they may suggest focused ultrasound surgery, a noninvasive procedure that doesn't require hospitalization. Your doctor uses an MRI scanner to see where the fibroids are, then targets them with focused sound waves that destroy them with heat.
Other procedures that can destroy uterine fibroids include:
- Uterine artery embolization, which cuts off the fibroids' blood supply so they shrink and eventually die
- Endometrial ablation, in which the inside lining of the uterus is removed, burned, or frozen
- Laparoscopic myolysis, in which freezing or an electric current is used to destroy the fibroids
Doctors aren't sure what causes fibroids, but the tumors seem to rely on estrogen to grow. After menopause, they often shrink naturally and cause no symptoms.
Adenomyosis is a condition in which tissue that normally lines the uterus (endometrium) moves into the uterus's muscular outer wall. This causes a widespread thickening of the uterus. When it affects only a small area, it's called an adenomyoma.
While the cause of adenomyosis is unknown, it usually affects women over 30 who've had children. It's more common in those who've have had uterine surgery, including a cesarean section.
In addition to uterine enlargement, symptoms may include:
- Long periods or heavy bleeding
- Painful periods, which get continually worse
- Pain during sex
Most women have some adenomyosis at the end of their childbearing years. Most don't require treatment, but some need medication to relieve pain. Birth control pills or an intrauterine device (IUD) containing progesterone may help lessen heavy bleeding. Women with serious symptoms may need a hysterectomy.
Other Causes of an Enlarged Uterus
In some cases, an enlarged uterus can be a symptom of uterine cancers, including endometrial cancer (which affects the lining of the uterus) and cervical cancer (which affects the lower part of the uterus where it joins the vagina). Treatment depends on the location, how widespread the cancer is, and other things.
Symptoms of an Enlarged Uterus
If you have an enlarged uterus, you won't necessarily notice it yourself. Your doctor may discover it during a physical exam or on imaging tests. Many conditions that cause an enlarged uterus are harmless and don't require treatment unless you have serious symptoms.
If you have problems like irregular bleeding; painful, heavy periods; pain during sex; or feelings of fullness or pressure in your lower belly, see your doctor. They can find the cause and the best treatment.