Uterine Fibroids

Uterine fibroids (also called leiomyomas) are growths made of muscle and tissue that form in or on the wall of your uterus. These growths are usually not cancerous (benign) and are the most common noncancerous tumor in women and people assigned female at birth (AFAB).

Uterine fibroids can cause a variety of symptoms like pain and heavy, irregular vaginal bleeding. Sometimes, a person has no symptoms and is unaware they have fibroids. Treatment for fibroids typically depends on your symptoms.

Where do fibroids grow?

Fibroids can grow as a single nodule (one growth) or in a cluster. Clusters of fibroids can range in size from 1 millimeter to more than 20 centimeters (8 inches) in diameter or even larger. For comparison, fibroids can be as small as a seed or get as large as a watermelon. These growths can develop within the wall of your uterus, inside the main cavity of your uterus or on the outer surface of your uterus.

Types of uterine fibroids

There are different types of uterine fibroids depending on where they’re located and how they attach. Specific types of uterine fibroids include:

• Intramural fibroids: These fibroids are embedded into the muscular wall of your uterus. They’re the most common type.
• Submucosal fibroids: These fibroids grow under the inner lining of your uterus.
• Subserosal fibroids: This type of fibroid grows under the lining of the outer surface of your uterus. They can become quite large and grow into your pelvis.
• Pedunculated fibroids: The least common type, these fibroids attach to your uterus with a stalk or stem. They’re often described as mushroom-like because they have a stalk and then a wider top.

Are fibroids common?

Fibroids are a very common type of growth. Approximately 40% to 80% of people with a uterus have fibroids. They occur most often in people between 30 and 50 years old. People who haven’t had their first period (menstruation) yet typically don’t have fibroids. They’re also less common in people who’ve entered menopause.