Uterine fibroids - symptoms and causes (2023)

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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 gynecologist at Mayo Clinic. In this video, we'll cover the basics of uterine fibroids. What is this? Who gets it? Symptoms, diagnosis and treatment. Whether you're looking for answers for yourself or someone you love. We are here to provide you with the best information available. Uterine fibroids, also called leiomyomas or fibroids, are growths that occur in the uterus. They are made of uterine muscle. They are not cancerous and are extremely common. In fact, 75-80% of people with a uterus will be diagnosed with fibroids at some point in their lives. These growths often appear during the reproductive years, most often between the ages of 20 and 30. They can vary in quantity, size and growth rate. So every case is a little different.

Who gets it?

We believe that uterine fibroids occur when a muscle cell divides repeatedly to create a firm, elastic mass of tissue. Scientists aren't yet sure exactly what causes this behavior, but we're looking at specific genes. We know a few risk factors that can make someone more prone to fibroids. First, race. For reasons that are not clear, fibroids are more common and more severe in black patients compared to other racial groups. Second, family history. If your mother or sister had fibroids, you are also at higher risk of developing them. And more studies are looking at other risk factors such as obesity, lifestyle choices and diet.

What are the symptoms?

Most people with fibroids have no symptoms. That's why they are often discovered inadvertently during a routine checkup. If a patient has symptoms, heavy, prolonged, or painful menstruation is a common problem. Periods that last more than a week or cause wet pads or tampons every hour or formation of large blood clots are also considered abnormal. If fibroids grow too large, they can cause your abdomen to swell like a pregnancy or put pressure on nearby organs, causing constant pelvic pressure, frequent or difficult bowel movements. In some cases, fibroids can make pregnancy difficult or cause problems during pregnancy or childbirth. If you experience any of these symptoms, talk to your doctor.

How is the diagnosis made?

Fibroids are often found during a routine pelvic exam. If your doctor feels an abnormality in the shape of the uterus, or if you arrive with symptoms, he or she will likely order a diagnostic test, such as an ultrasound. Beyond that, your doctor may need more information, especially if you're trying to get pregnant or are at risk for uterine cancer. They may order blood tests or imaging studies such as an MRI. Other unique imaging tests that use water to see inside the uterus or dye to check the fallopian tubes are sometimes 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 may be found. All of these tests are done to get a better, clearer picture of what's going on or to find other problems.

How is it treated?

There are many ways 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 close eye on your fibroids until further action is needed. Medication or birth control is another option that can relieve symptoms such as heavy, irregular, or painful periods. For some more severe cases, surgery may be needed. The type of surgery we recommend depends on the size, number, and location of the fibroids, as well as your personal goals, your feelings about the pregnancy and surgery, and your general health. A hysterectomy is where the uterus and fibroids are removed together. And it's a great option for those who don't want to get pregnant, since it guarantees that there will be no more period bleeding and that fibroids won't reappear in the future. Myomectomy is a surgical procedure in which we remove fibroids through the vagina or abdominal wall. Uterine fibroid embolization is a small procedure in which we block the blood supply to the fibroids, causing them to shrink but not disappear completely. Radiofrequency fibroid ablation involves inserting a probe into the fibroid and heating the tissue to shrink it. MRI-guided focused ultrasound delivers energy through the abdomen to destroy the fibroid. Finally, endometriosis is a procedure in which a device is inserted through the vagina to treat the lining of the uterus and stop heavy menstrual bleeding due to fibroids. But this does not treat the fibroids themselves.

And now what?

Fibroids are common, non-cancerous and often do not require treatment. Whether you end up needing treatment or not, know that there are many options that can address your concerns and give you an excellent quality of life. Talk to your doctor or get a referral to a fibroid specialist to make sure all treatment options are offered. If you want to learn more about fibroids, check out our other related videos or visit mayoclinic.org. We wish you the best.

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Uterine fibroids - symptoms and causes (1)

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There are three main types of uterine fibroids. Intramuscular fibroids develop within the muscular wall of the uterus. Submucous fibroids protrude into the uterine cavity. Subserous fibroids project to the outside of the uterus. Some submucosal or subserous fibroids may be pedunculated, hanging from a stalk inside or outside the uterus.

Uterine fibroids are non-cancerous growths of the uterus that often occur during childbearing years. Also called leiomyomas (lie-o-my-O-muhs) or fibroids, uterine fibroids are not associated with an increased risk of uterine cancer and almost never develop into cancer.

Fibroids vary in size from spores, imperceptible to the human eye, to massive masses that can distort and enlarge the uterus. You may have a single fibroid or many. In extreme cases, multiple fibroids can expand the uterus so far that it reaches the rib and adds weight.

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


Many women who have fibroids have no symptoms. In those who do, symptoms can be affected 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
  • Menstruation lasting more than a week.
  • Pelvic pressure or pain
  • frequent urination
  • Difficulty emptying the bladder
  • Constipation
  • Pain in the back or legs

Rarely, a fibroid can cause sharp pain as it overwhelms the blood supply and begins to die.

Fibroids are generally classified based on their location. Intramuscular fibroids develop within the muscular wall of the uterus. Submucous fibroids protrude into the uterine cavity. Subserous fibroids project to the outside of the uterus.

When to see a doctor

See your doctor if you have:

  • Pelvic pain that does not go away
  • Periods that are very heavy, prolonged or painful
  • Spotting or bleeding between periods
  • Difficulty emptying the bladder
  • Unexplained low red blood cell count (anaemia)

Get immediate medical help if you have severe vaginal bleeding or sharp pelvic pain that comes on suddenly.

Request an appointment

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Doctors do not know the cause of uterine fibroids, but research and clinical experience point to these factors:

  • Genetic changes.Many fibroids contain gene changes that differ from those of typical uterine muscle cells.
  • hormonesEstrogen and progesterone, two hormones that stimulate the growth of the lining of the uterus 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. Fibroids tend to shrink after menopause due to a decrease in hormone production.

  • Other growth factors.Substances that help the body maintain tissue, such as insulin-like growth factor, can affect the growth of fibroids.
  • Extracellular matrix (ECM). ECMit's the stuff that makes cells stick together, like mortar between bricks.ECMit increases fibroids and makes them fibrous.ECMIt also stores growth factors and causes biological changes in the cells themselves.

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

The growth patterns of uterine fibroids vary: they can grow slowly or quickly, or they can stay the same size. Some fibroids show growth spurts and some may shrink on their own.

Many fibroids that were present during pregnancy shrink or disappear after pregnancy as the uterus returns to its usual size.

Risk factors

There are few known risk factors for uterine fibroids other than being a woman of childbearing age. Factors that can affect the development of fibroids include:

  • Carrera.Although all women of childbearing age can develop fibroids, black women are more likely to have fibroids than women of other racial groups. Also, black women have fibroids at younger ages and are also likely to have more or larger fibroids, along with more severe symptoms.
  • Legacy.If your mother or sister had fibroids, you are at a higher risk of developing them.
  • Other factors.Starting your period at a young age. portliness; vitamin D deficiency; they have a diet rich in red meat and low in vegetables, fruits and dairy products. and drinking alcohol, including beer, appears to increase the risk of fibroids.


Although uterine fibroids are usually not dangerous, they can cause discomfort and can lead to complications, such as a decrease in red blood cells (anaemia), which causes fatigue, due to extensive blood loss. A transfusion is rarely needed due to blood loss.

Pregnancy and fibroids

Fibroids usually do not prevent pregnancy. However, it is possible for fibroids, especially submucosal fibroids, to cause infertility or pregnancy loss.

Fibroids can also increase the risk of certain pregnancy complications, such as placental abruption, fetal growth restriction, and premature birth.


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

However, by making healthy lifestyle choices, such as maintaining a healthy weight and eating fruits and vegetables, you may be able to reduce your risk of fibroids.

In addition, some research suggests that using hormonal birth control may be associated with a lower risk of fibroids.

By the Mayo Clinic staff

September 21, 2022

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