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Uterine Fibroids

What are uterine fibroids?

Fibroids are firm, dense tumors made of smooth muscle cells and fibrous connective tissue. They develop in the uterus. About 1 in 5 to 1 in 2 women of reproductive age have fibroids, but not all are diagnosed. Some estimates say that up to 3 in 10 to about 3 in 4women will have fibroids sometime during their childbearing years. Only about one-third of these fibroids are large enough to be found by a healthcare provider during a physical exam.

In more than 9 in 10 fibroid cases, the tumors are not cancer. These tumors are not linked to cancer and don't increase a woman's risk for uterine cancer. They may be as small as a pea to as large as a softball or small grapefruit.

What causes uterine fibroid tumors?

Doctors don't know what causes uterine fibroids. It may be that each tumor develops from an abnormal muscle cell in the uterus. This cell multiplies rapidly because of the effect of estrogen.

Who is at risk for uterine fibroids?

Women who are nearing menopause are at the greatest risk for fibroids. This is because of their long exposure to high levels of estrogen. Women who are obese and of African-American background also seem to be at higher risk. The reasons for this are not clearly understood.

Other risk factors: 

  • Diet high in red meat
  • Family history of fibroids
  • High blood pressure

What are the symptoms of uterine fibroids?

Some women who have fibroids have no symptoms. Or they have only mild symptoms. Other women have more severe symptoms. These are the most common symptoms for uterine fibroids:

  • Heavy or lengthy periods
  • Abnormal bleeding between periods
  • Pelvic pain. This happens as the tumor presses on pelvic organs
  • Frequent urination
  • Low back pain
  • Pain during intercourse
  • A firm mass often near the middle of the pelvis. This can be felt by your healthcare provider.

How are uterine fibroids diagnosed?

Fibroids are most often found during a routine pelvic exam. Your healthcare provider may feel a firm, irregular pelvic mass during an abdominal or pelvic exam. You may need other tests. These include:

  • X-ray. Beams of energy make images of bones and internal organs on film.
  • Transvaginal ultrasound. This is an ultrasound test using a small tool (transducer) that is placed in the vagina.
  • MRI. This test uses a large magnet, radio waves, and a computer to make 2-D images of an internal organ or structure.
  • Hysterosalpingography. This is an X-ray exam of the uterus and fallopian tubes that uses dye. It's often done to rule out blocked fallopian tubes.
  • Hysteroscopy. For this test, the healthcare provider uses a viewing tool (hysteroscope) to look at the canal of the cervix and the inside of the uterus. The tool is inserted through the vagina.
  • Endometrial biopsy. For this procedure, the healthcare provider takes a sample of tissue through a tube inserted into the uterus.
  • Blood test. This is to check for iron-deficiency anemia if the fibroid causes heavy bleeding.

How are uterine fibroids treated?

Most fibroids stop growing or may even shrink as you get near menopause. Your healthcare provider may suggest "watchful waiting." With this approach, your healthcare provider monitors your symptoms carefully to make sure you have no significant changes. He or she will check that the fibroids are not growing.

If your fibroids are large or cause a lot of symptoms, you may need treatment. Treatment will depend on your age and if you want to get pregnant in the future.

In general, treatment for fibroids may include:

  • Hysterectomy. This is the surgical removal of the entire uterus. Fibroids are the main reason for hysterectomies in the U.S.
  • Conservative surgical therapy. Conservative surgical therapy uses a procedure called a myomectomy. With this approach, fibroids are removed, but the uterus stays intact. This may allow a future pregnancy.
  • Gonadotropin-releasing hormone agonists (GnRH agonists). This approach lowers your estrogen level. This triggers a "medical menopause." Sometimes GnRH agonists are used to shrink the fibroid to make surgery easier.
  • Anti-hormonal medicines. Certain medicines such as progestin block estrogen and seem to work to treat fibroids. Anti-progestins block the action of progesterone. They are also sometimes used.
  • Uterine artery embolization. This is also called uterine fibroid embolization. The healthcare provider finds the arteries supplying blood to the fibroids. Then the provider blocks them off (embolizes them). This cuts off the blood supply to the fibroids and shrinks them. Healthcare providers are studying the long-term effects of this procedure on fertility and regrowth of the fibroid tissue.
  • Anti-inflammatory painkillers. This type of medicine often works well for women who have occasional pelvic pain or discomfort.

In some cases,heavy or lengthy periods, or abnormal bleeding between periods can lead to iron-deficiency anemia. You will need treatment for this.

What are possible complications of uterine fibroids?

Uterine fibroids may affect the reproductive system. They can cause infertility, increased risk for miscarriage, or problems during pregnancy.

Key points about uterine fibroids

  • Uterine fibroids are firm, dense tumors that are made of smooth muscle cells and fibrous connective tissue that develop in the uterus. 
  • Fibroids are not cancer and don't increase a woman's risk for uterine cancer.
  • Women who are nearing menopause are at the greatest risk for fibroids. This is because of their long exposure to high levels of estrogen.
  • Symptoms may include heavy and prolonged periods, bleeding between periods, and pelvic pain.
  • Fibroids are most often found during a routine pelvic exam.
  • If treatment is needed, it may include medicines or surgery.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
  • Ask if your condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if you do not take the medicine or have the test or procedure.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.
Online Medical Reviewer: Donna Freeborn PhD CNM FNP
Online Medical Reviewer: Heather Trevino
Online Medical Reviewer: Irina Burd MD PhD
Date Last Reviewed: 11/1/2018
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