What are uterine fibroids?

Uterine fibroids are tumors or lumps made of muscle cells and other tissue that grow within the wall of the uterus. Although fibroids are called “tumors,” they are not cancer. Fibroids may grow as a single tumor or in clusters. A single fibroid can be less than 1 inch in size or can grow to 8 inches across or more. A bunch or cluster of fibroids also can vary in size. Most of the time fibroids grow in women of childbearing age. It is estimated that as many as 77 percent of women of childbearing age could have the condition without knowing it.

Where do uterine fibroids grow?

Doctors put fibroids into three groups based on where they grow, such as just underneath the lining of the uterus, in between the muscles of the uterus, or on the outside of the uterus. Most fibroids grow within the wall of the uterus. Some fibroids grow on stalks (called peduncles) that grow out from the surface of the uterus, or into the cavity of the uterus.

What are the symptoms of uterine fibroids?

Many women don’t feel any symptoms with uterine fibroids. But fibroids can cause the following:

• heavy or painful periods

• bleeding between periods

• feeling "full" in the lower abdomen - sometimes called "pelvic pressure"

• urinating often (from a fibroid pressing on the bladder)

• pain during sex

• lower back pain

• reproductive problems, such as infertility, multiple miscarriages and early onset of labor during pregnancy

What causes uterine fibroids?

Currently, little is known about what causes uterine fibroids. Scientists have a number of theories, but none of these ideas explains fibroids completely. Most likely, fibroids are the end result of many factors interacting with each other. These factors could be genetic, hormonal, environmental or a combination of all three.

Who gets uterine fibroids?

Most of the time fibroids grow in women of childbearing age, but can be found in women of all ages. Researchers now recognize several risk factors for uterine fibroids:

• African-American women are three to five times at greater risk than white women.

• Women who are overweight or obese for their height (based on body mass index or BMI) are at slightly higher risk.

• Women who have given birth appear to be at lower risk.

How are fibroids diagnosed?

Usually, fibroids are found by abdominal or pelvic examination or pelvic ultrasound. To confirm a diagnosis, your health care provider may use imaging technology such as ultrasound, magnetic resonance imaging (MRI), X-rays or a CT “cat”- scan. Sometimes the only way to confirm the diagnosis is through surgery.

• Laparoscopy — the surgeon makes a small cut into the abdomen, after inflating it with a harmless gas; then, using a small viewing instrument containing a light, the doctor can look for fibroids.

• Hysteroscopy — the surgeon inserts a camera on a long tube through the vagina directly into the uterus to see the fibroids.

How are fibroids treated?

There are several factors to consider when recommending treatment for fibroids.

• Does the woman have symptoms of uterine fibroids?

• Does she want to become pregnant?

• How large are the fibroids?

• What is the woman’s age?

If a woman has many symptoms or feels pain often, medical therapy may be considered.

• Pain medication may relieve symptoms.

• Gonadotropin releasing hormone agonists block the body from making the hormones that cause women to menstruate or have their periods. If you have symptoms, have health conditions that make surgery less advisable and are near menopause or do not want children, you may consider this treatment.

• Antihormonal agents, like mifepristone, will slow or stop the growth of fibroids.

If a woman has moderate symptoms, surgery may be the best form of treatment.

• Myomectomy removes only the fibroids and leaves the healthy tissue of the uterus in place.

• Hysterectomy is used when a woman's fibroids are large, or has heavy bleeding and she is either near or past menopause or does not want children.

• Endometrial ablation destroys the endometrial lining of the uterus. It controls very heavy bleeding, but afterwards a woman might not be able to have children.

• Myolysis is a procedure in which an electrical needle is used to destroy the blood vessels feeding the fibroids

Do uterine fibroids lead to cancer?

Uterine fibroids are not cancerous. Fibroids are not associated with cancer. They do not increase your risk for uterine cancer.

More information about uterine fibroids can be obtained by contacting:

National Institute of Child Health and Human Development
800-370-2943
http://www.nichd.nih.gov/health/topics/uterine_fibroids.cfm

Agency for Healthcare Research and Quality
800-358-9295
www.ahrq.gov

National Women’s Health Information Center
800-994-9662
http://www.4woman.gov/faq/fibroids.htm