Medically Reviewed by Nivin Todd, MD on May 31, 2020

What Are Uterine Fibroids?

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Uterine fibroids are noncancerous growths of the muscle tissue of the uterus. Fibroids can range in number and size from a single growth to multiple growths, and from very small to large. As many as 70% to 80% of all women will have fibroids by age 50. The medical term for fibroids is leiomyoma or myoma.

Symptoms of Fibroids: Pressure

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Fibroids may cause very mild symptoms, none at all or symptoms can be severe. In women who do feel symptoms, these uterine growths can cause:

  • Pressure on the bladder or rectum
  • Frequent urination
  • Constipation and/or rectal pain
  • Lower back and/or abdominal pain

If fibroids become very large, they can distend the stomach, making a woman look pregnant.

Symptoms of Fibroids: Period Changes

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Fibroids may also cause changes to a woman's period, including:

  • Mild to severe cramping and pain
  • Heavier bleeding, sometimes with blood clots
  • Longer or more frequent menstruation
  • Spotting or bleeding between periods

Fibroids or Endometriosis?

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Fibroids are one cause of severe menstrual pain, but the pain also can be caused by endometriosis. Endometriosis occurs when tissue from the inner lining of the uterus grows in other parts of the body -- illustrated here by growths on the outside of the uterus and bladder. This tissue breaks down and bleeds during your period, causing pain during your cycle and painful scar tissue. The pain of fibroids or endometriosis also can occur between periods.

What Causes Fibroids?

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The exact cause of fibroids is unknown. Their growth has been linked to the female hormones estrogen and progesterone. Studies have found that women who start their periods at a younger age are more likely to develop fibroids. Although taking female hormones is linked to fibroids, the use of birth control pills is not.

Types of Fibroids

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  • Intramural fibroids, the most common, grow in the wall of the uterus.
  • Subserosal fibroids grow on the outside of the uterus. As they grow larger, they can cause pain due to their size or pressure put on nearby organs.
  • Submucosal fibroids grow just underneath the uterine lining and can crowd into the uterus cavity and lead to heavy bleeding and other more serious complications.
  • Pedunculated fibroids grow on small stalks inside or outside the uterus. 

It's possible to have more than one type of fibroid.

Who Gets Fibroids?

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While it's unclear why women develop fibroids, some patterns have been observed.

  • They usually occur between the ages of 30 and 40.
  • They are more common in black women.
  • They grow more quickly and appear at a younger age in black women.
  • Having a family member with fibroids increases a woman's risk.
  • Being overweight or obese and having high blood pressure also may increase your risk.

Complications: Fibroids and Anemia

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Some women with fibroids who experience unusually heavy bleeding during their periods may become anemic. Many cases of anemia due to iron deficiency from periods are mild and can be treated with a change in diet and iron supplement pills. Untreated anemia can lead to fatigue and lethargy -- and, in severe cases, heart problems.

Complications: Getting Pregnant

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Fibroids usually do not interfere with fertility and pregnancy. However, some women with fibroids experience more pregnancy complications and delivery risks. Fibroids may cause the baby to be in an abnormal position and can cause preterm labor. They may also cause pelvic pain and heavy bleeding after delivery, which may require surgery. In some instances, fibroids may block your fallopian tubes. Fibroids growing along the inner uterine wall may make it difficult for a fertilized egg to attach. 

When to See a Doctor

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See your health care provider if you have the following fibroid symptoms:

  • Heavy menstrual bleeding
  • Periods that became more painful
  • Frequent urination or inability to control the flow of urine
  • A change in the length of your period over three to six cycles
  • New persistent pain or heaviness in lower abdomen or pelvis

Diagnosis: Exam and Imaging

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Your doctor may feel moderate and large uterine fibroids during a routine pelvic exam. Tests, such as an ultrasound, can show information about size and location of other fibroids. For women with fibroids who are trying to get pregnant, a test called a hysterosalpingogram will show an outline of the uterus and fallopian tubes and may detect abnormalities. Other procedures to visualize the inside of the uterus or abdomen also may be needed.

Treatment: Pain Medication

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Pain medications, such as acetaminophen, and nonsteroidal anti-inflammatory drugs (NSAIDs), like as ibuprofen or naproxen, can help relieve menstrual cramping.

Treatment: Birth Control

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Oral contraceptives manage levels of estrogen and progestin. This usually leads to lighter periods and can alleviate some of the pain associated with fibroids, such as heavy bleeding and cramping. Other hormonal birth control methods that may lessen fibroid symptoms include progestin injections or progestin-releasing IUDs.

Other Hormone Therapies

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Drugs called gonadotropin-releasing hormone (GnRH) agonists may offer temporary symptom relief from fibroids by stopping periods and shrinking fibroids. GnRH agonists block the production of estrogen, so they can also cause bone loss, hot flashes, and vaginal dryness. Fibroids will return to their previous size once treatment ends. These may be used to shrink fibroids before fibroid removal surgery.

Treatment: Embolization

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For mild to moderate symptoms, uterine fibroid embolization may be a good option. A catheter is guided to the uterine artery. Tiny particles of plastic or gelatin are then released into the blood vessels that feed the fibroid, causing it to shrink over time. Embolization should not be an option for women wanting to get pregnant at some point after treatment.

Treatment: Surgery

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A myomectomy typically removes the largest fibroids. It’s is an option for women who want to still have children. A hysterectomy is when the uterus is removed. There is a small chance that what was thought to be a fibroid could instead be a cancer called uterine sarcoma. For this reason, the FDA recommends not cutting the fibroid into small sections before removing it, a process called laparoscopic morcellation. Endometrial ablation, which is good for treating smaller fibroids, destroys the lining of the uterus, so pregnancy is not possible.

Treatment: Ultrasound

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Ultrasound is one way to destroy fibroids without risk of damaging the uterus. The treatment uses high-intensity ultrasound waves that kill the fibroid tissue. Most women recover quickly from this procedure and can return to regular activities within 24 hours. The long-term effects are still being studied, and it is not recommended for women who want to become pregnant.

Fibroid Remedy: Exercise

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Regular exercise may prevent fibroids. In one study, women who exercised seven or more hours a week had significantly fewer fibroids than women who exercised less than two hours a week. Obesity also is a risk factor for fibroids. So exercising regularly can help you maintain a healthy weight and reduce your fibroid risk.

Care for Anemia

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Women with fibroids who are not getting enough iron through diet alone may develop anemia, where the body has fewer red blood cells than normal. Symptoms include fatigue, chest pain, and shortness of breath. Treatment may include eating more iron-rich foods, such as meats, poultry, fish, leafy greens, legumes, and iron-fortified breads and cereals. Your health care provider also may suggest iron supplements.

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Show Sources


(1)      Peggy Firth and Susan Gilbert for WebMD
(2)      CNRI / Photo Researchers
(3)      Alix Minde/PhotoAlto
(4)      Peggy Firth and Susan Gilbert for WebMD
(5)      Dr. Barry Slaven/Visuals Unlimited
(6)      Peggy Firth and Susan Gilbert for WebMD
(7)      Priscilla Gragg/Blend Images
(8)      Thomas Deerinck, NCMIR/SPL
(9)      Lawren/Flickr
(10)    Keith Brofsky/Photodisc
(11)    Dr. Pichard T/Photo Researchers
(12)    Grove Pashley/Photographer's Choice
(13)    Sarah M. Golonka/Brand X
(14)    Nenov/Flickr
(15)    Peggy Firth and Susan Gilbert for WebMD
(16)    Dr. Najeeb Layyous/Photo Researchers
(17)    Chru Tours-Garo, PHANIE/Photo Researchers
(18)    Assembly/Photodisc
(19)    Kate Brittle/Flickr


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