Overview

What are uterine fibroids? A Mayo Clinic expert explains

Learn more about uterine fibroids from Michelle Louie, M.D., a minimally invasive gynecologic surgeon at Mayo Clinic.

I'm Dr. Michelle Louie, a minimally invasive gynecologic surgeon at Mayo Clinic. In this video, we'll cover the basics of uterine fibroids. What is it? Who gets it? The symptoms, diagnosis, and treatment. Whether you're looking for answers for yourself or someone you love. We're here to give you the best information available. Uterine fibroids, also called leiomyomas or myomas, are growths that appear in the uterus. They're made of uterine muscle. They're noncancerous and extremely common. In fact, 75 to 80% of people with a uterus will be diagnosed with fibroids at some point in their lives. These growths often show up during the reproductive years, most commonly in your 20s to 30s. They can range in quantity, size and growth rate. So each case is a bit different.

Who gets it?

We believe uterine fibroids occur when one cell of muscle divides repeatedly to create a firm, rubbery mass of tissue. Scientists are not yet sure exactly what sparks this behavior, but we're looking into specific genes. We do know a couple of risk factors that may make someone more likely to get fibroids. First, race. For reasons that are unclear, fibroids are more prevalent and more severe among black patients compared to other racial groups. Second, family history. If your mother or sister had fibroids, you're at increased risk for developing them, too. And more studies look into other risk factors like obesity, lifestyle choices, and diet.

What are the symptoms?

Most people with fibroids don't have symptoms at all. That's why they're often found unintentionally during a routine checkup. If a patient does have symptoms, heavy, prolonged, or painful menstrual bleeding is a common problem. Periods that lasts more than one week or cause soaking through pads or tampons every hour or large blood clots are also considered abnormal. If fibroids get very large, they can cause your belly to bulge like a pregnancy or press on nearby organs causing constant pelvic pressure, frequent urination, or difficulty passing bowel movements. In some cases, fibroids can make it harder to get pregnant or cause problems during pregnancy or childbirth. If you're experiencing any of these symptoms, talk to your doctor.

How is it diagnosed?

Fibroids are often found during a routine pelvic exam. If your doctor feels an irregularity in the shape of the uterus or if you come in with symptoms, they'll probably order a diagnostic test like an ultrasound. Beyond that, your doctor may need more information, especially if you're trying to get pregnant or at risk for uterine cancer. They might order blood tests or imaging studies like an MRI. Sometimes other unique imaging studies that use water to see inside the uterus or dye to check the fallopian tubes are needed if you're trying to get pregnant. Even hysteroscopy, in which a small camera is guided through the vagina, is sometimes used to see inside the uterus where some fibroids can be located. All these tests are done in service of getting a better, clearer picture of what's going on or to check for other problems.

How is it treated?

There are many ways in which we treat uterine fibroids. If you have no or only mild symptoms, as many women do, the best treatment may be no treatment at all. We call this watchful waiting where we keep a careful eye on your fibroids until further action is needed. Medication or birth control is another option which can relieve symptoms like heavy, irregular or painful periods. For some more severe cases, surgery may be needed. The kind of surgery we recommend depends on the size, number, and location of fibroids, as well as your personal goals, feelings about pregnancy and surgery, and general health. A hysterectomy is where the uterus and the fibroids are removed together. And it is a great option for those who have no desire for pregnancy as it guarantees no more period bleeding and the fibroids cannot return in the future. A myomectomy is a surgery in which we remove the fibroids through the vagina or the abdominal wall. Uterine fibroid embolization is a more minor procedure in which we blocked the blood supply to the fibroids, causing them to shrink but not go away completely. A radiofrequency fibroid ablation is where a probe is inserted into the fibroid and heats the tissue, so it shrinks. Magnetic resonance-guided focused ultrasound passes energy through the abdomen to destroy the fibroid. Lastly, an endometrial ablation is a procedure in which a device is inserted through the vagina to treat the uterine lining, and stop heavy period bleeding due to fibroids. But this does not treat the fibroids themselves.

What now?

Fibroids are common, noncancerous and often don't need treatment. Whether or not you do end up needing treatment, know that there are many options that can address your concerns and give you a great quality of life. Talk to your doctor or get a referral to a fibroid specialist to ensure that you are offered all the treatment options. If you'd like to learn more about fibroids, watch our other related videos, or visit mayoclinic.org. We wish you well.

Uterine fibroids are noncancerous growths of the uterus that often appear during childbearing years. Also called leiomyomas (lie-o-my-O-muhs) or myomas, uterine fibroids aren't associated with an increased risk of uterine cancer and almost never develop into cancer.

Fibroids range in size from seedlings, undetectable by the human eye, to bulky masses that can distort and enlarge the uterus. You can have a single fibroid or multiple ones. In extreme cases, multiple fibroids can expand the uterus so much that it reaches the rib cage and can add weight.

Many women have uterine fibroids sometime during their lives. But you might not know you have uterine fibroids because they often cause no symptoms. Your doctor may discover fibroids incidentally during a pelvic exam or prenatal ultrasound.

Symptoms

Many women who have fibroids don't have any symptoms. In those that do, symptoms can be influenced by the location, size and number of fibroids.

In women who have symptoms, the most common signs and symptoms of uterine fibroids include:

  • Heavy menstrual bleeding
  • Menstrual periods lasting more than a week
  • Pelvic pressure or pain
  • Frequent urination
  • Difficulty emptying the bladder
  • Constipation
  • Backache or leg pains

Rarely, a fibroid can cause acute pain when it outgrows its blood supply, and begins to die.

Fibroids are generally classified by their location. Intramural fibroids grow within the muscular uterine wall. Submucosal fibroids bulge into the uterine cavity. Subserosal fibroids project to the outside of the uterus.

When to see a doctor

See your doctor if you have:

  • Pelvic pain that doesn't go away
  • Overly heavy, prolonged or painful periods
  • Spotting or bleeding between periods
  • Difficulty emptying your bladder
  • Unexplained low red blood cell count (anemia)

Seek prompt medical care if you have severe vaginal bleeding or sharp pelvic pain that comes on suddenly.

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Causes

Doctors don't know the cause of uterine fibroids, but research and clinical experience point to these factors:

  • Genetic changes. Many fibroids contain changes in genes that differ from those in typical uterine muscle cells.
  • Hormones. Estrogen and progesterone, two hormones that stimulate development of the uterine lining during each menstrual cycle in preparation for pregnancy, appear to promote the growth of fibroids.

    Fibroids contain more estrogen and progesterone receptors than typical uterine muscle cells do. Fibroids tend to shrink after menopause due to a decrease in hormone production.

  • Other growth factors. Substances that help the body maintain tissues, such as insulin-like growth factor, may affect fibroid growth.
  • Extracellular matrix (ECM). ECM is the material that makes cells stick together, like mortar between bricks. ECM is increased in fibroids and makes them fibrous. ECM also stores growth factors and causes biologic changes in the cells themselves.

Doctors believe that uterine fibroids develop from a stem cell in the smooth muscular tissue of the uterus (myometrium). A single cell divides repeatedly, eventually creating a firm, rubbery mass distinct from nearby tissue.

The growth patterns of uterine fibroids vary — they may grow slowly or rapidly, or they may remain the same size. Some fibroids go through growth spurts, and some may shrink on their own.

Many fibroids that have been present during pregnancy shrink or disappear after pregnancy, as the uterus goes back to its usual size.

Risk factors

There are few known risk factors for uterine fibroids, other than being a woman of reproductive age. Factors that can have an impact on fibroid development include:

  • Race. Although all women of reproductive age could develop fibroids, black women are more likely to have fibroids than are women of other racial groups. In addition, black women have fibroids at younger ages, and they're also likely to have more or larger fibroids, along with more-severe symptoms.
  • Heredity. If your mother or sister had fibroids, you're at increased risk of developing them.
  • Other factors. Starting your period at an early age; obesity; a vitamin D deficiency; having a diet higher in red meat and lower in green vegetables, fruit and dairy; and drinking alcohol, including beer, appear to increase your risk of developing fibroids.

Complications

Although uterine fibroids usually aren't dangerous, they can cause discomfort and may lead to complications such as a drop in red blood cells (anemia), which causes fatigue, from heavy blood loss. Rarely, a transfusion is needed due to blood loss.

Pregnancy and fibroids

Fibroids usually don't interfere with getting pregnant. However, it's possible that fibroids — especially submucosal fibroids — could cause infertility or pregnancy loss.

Fibroids may also raise the risk of certain pregnancy complications, such as placental abruption, fetal growth restriction and preterm delivery.

Prevention

Although researchers continue to study the causes of fibroid tumors, little scientific evidence is available on how to prevent them. Preventing uterine fibroids may not be possible, but only a small percentage of these tumors require treatment.

But, by making healthy lifestyle choices, such as maintaining a healthy weight and eating fruits and vegetables, you may be able to decrease your fibroid risk.

Also, some research suggests that using hormonal contraceptives may be associated with a lower risk of fibroids.

Uterine fibroids care at Mayo Clinic

Sept. 21, 2022
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