What Are Fibroids?

Fibroids are firm, compact tumors that develop in or on a woman’s uterus. They may range in size, from the size of a pea to the size of a softball or small grapefruit. Fibroids are also known as uterine myomas, leiomyomas or fibromas. Types of fibroids include:

• Intramural: The most common type of fibroid, this tumor appears within the lining of the uterus (endometrium).
• Submucosal: Tumors that develop in the inner lining of the uterus (myometrium).
• Suberosal: These form outside the uterus, called the serosa.

Are fibroids cancerous?

In more than 99 percent of fibroid cases, the tumors are benign (non-cancerous). These tumors are not associated with cancer and do not increase a woman's risk for uterine cancer.

Physicians estimate that between 20 to 30 percent of women of reproductive age have fibroids, though they are not always diagnosed. Some estimates state that up to 75 percent of women will develop fibroids sometime during their childbearing years. However, only about one-third of these fibroids are large enough for a physician to detect during a physical examination.

Who is at risk for fibroids?

Women who have the highest risk for developing fibroids are:

• Approaching menopause, because of their long exposure to high levels of estrogen.
• Obese
• Of African-American heritage, although the reasons for this are not clearly understood

Some studies have shown that that women who have given birth to two children have one-half the risk of developing uterine fibroids compared to women who have had no children. However, scientists are not sure whether having children protects women from fibroids or whether the fibroids were a factor in infertility in women who had no children.

The National Institute of Child Health and Human Development is conducting further research on this topic and other factors that may affect the diagnosis and treatment of fibroids.

Fibroid symptoms

Women’s experiences range from no symptoms to severe symptoms that disrupt their daily life. Common fibroid symptoms may include:

• Heavy menstrual periods
• Abnormal bleeding between periods
• Painful intercourse

Learn more about fibroid symptoms.

Diagnosing fibroids

Many times, especially if a woman did not experience symptoms, doctors find fibroids during a routine pelvic examination. To confirm a diagnosis, we may recommend one or more diagnostic procedures including:

• X-ray
• Magnetic resonance imaging
• Transvaginal ultrasound

Learn more about diagnosing fibroids.

Treatment of fibroids 

Your treatment plan for fibroids will depend on how severe your symptoms are and whether the fibroid is growing or not. Treatment options include:

• "Watchful waiting": We carefully monitor you to make sure the fibroids aren’t growing
• Medication to treat pelvic pain
• Surgical procedures, ranging from a myomectomy (removing the fibroids) to a hysterectomy (removing all or part of the uterus).

Learn more about fibroid treatment.