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(Leiomyomas; Myomas)


David G. Mutch

, MD, Washington University School of Medicine;

Scott W. Biest

, MD, Washington University School of Medicine

Full review/revision Dec 2020 | Modified Sep 2022
Topic Resources

A fibroid is a noncancerous tumor composed of muscle and fibrous tissue. It is located in the uterus.

  • Fibroids can cause pain, abnormal vaginal bleeding, constipation, repeated miscarriages, and an urge to urinate frequently or urgently.

  • Doctors do a pelvic examination and usually ultrasonography to confirm the diagnosis.

  • Treatment is necessary only if fibroids cause problems.

  • Doctors may prescribe drugs to control the symptoms, but surgery or a procedure to destroy the fibroids is often needed to relieve symptoms or to make childbirth possible.

Fibroids are also called leiomyomas or myomas.

The Uterus, Cervix, and Cervical Canal

Fibroids in the uterus are the most common noncancerous tumor of the female reproductive tract. By age 45, about 70% of women develop at least one fibroid. Many fibroids are small and cause no symptoms. But about one fourth of white women and one half of black women eventually develop fibroids that cause symptoms. Fibroids are more common among women who are overweight.

Did You Know...

  • By age 45, about 7 out of 10 women develop fibroids of the uterus.

What causes fibroids to grow in the uterus is unknown. High levels of estrogen and possibly progesterone (female hormones) seem to stimulate their growth. Fibroids may become larger during pregnancy (when levels of these hormones increase), and fibroids tend to shrink after menopause (when levels decrease drastically).

If fibroids grow too large, they may not be able to get enough blood. As a result, they begin to degenerate and cause pain.

Fibroids may be microscopic or as large as a basketball.

Fibroids may grow in different parts of the uterus, usually in the wall (which has three layers):

  • Under the outer surface of the uterus (subserosal fibroids)

  • In the wall of the uterus (intramural fibroids)

  • Under the inside layer (lining or endometrium) of the uterus (submucosal fibroids)

Subserosal fibroids are the most common type.

Some fibroids grow from a stalk (called pedunculated fibroids). Some submucosal fibroids extend into the interior of the uterus (called intracavitary fibroids). Fibroids that grow in the wall or just under the endometrium can distort the shape of the interior of the uterus.

Often, women have more than one fibroid.

Very rarely, fibroids become cancerous.

Where Fibroids Grow

Fibroids can grow in different parts of the uterus:

  • Under the outer surface of the uterus (subserosal fibroids)

  • In the wall of the uterus (intramural fibroid)

  • Under the lining of the uterus (submucosal fibroid)

Some fibroids grow on a stalk. They are called pedunculated fibroids.

Where Fibroids Grow

Symptoms of Fibroids

Symptoms depend on

  • The number of fibroids

  • Their size

  • Their location in the uterus

Many fibroids do not cause symptoms. The larger the fibroid, the more likely it is to cause symptoms. Fibroids, particularly those just under the lining, commonly make menstrual bleeding heavier or last longer than usual. Anemia may result from the loss of blood.

Large fibroids may cause pain, pressure, or a feeling of heaviness in the pelvic area during or between menstrual periods. Fibroids may press on the bladder, making a woman need to urinate more frequently or more urgently. They may press on the rectum, causing discomfort and constipation. They may interfere with how organs function—for example, by blocking the urinary tract and thus the flow of urine out of the body. Large fibroids may cause the abdomen to enlarge.

A fibroid growing on a stalk may twist, cutting off its blood supply, and cause severe pain.

Fibroids that are growing or degenerating can cause pressure or pain. Pain due to degenerating fibroids can last as long as they continue to degenerate.

Fibroids that cause no symptoms before pregnancy may cause problems during pregnancy. Problems include

Fibroids can cause infertility Overview of Infertility Infertility is usually defined as the inability to achieve a pregnancy after 1 year of regular sexual intercourse without birth control. Frequent intercourse without birth control usually results... read more Overview of Infertility by blocking the fallopian tubes or by distorting the shape of the uterus, making attachment to the lining of the uterus (implantation) of a fertilized egg difficult or impossible (see figure From Egg to Embryo Symptoms Symptoms ).

Fewer than 1% of fibroids become cancerous.

Diagnosis of Fibroids

  • Imaging, usually ultrasonography

Doctors may suspect fibroids based on results of a pelvic examination. However, imaging tests are often needed to confirm the diagnosis of uterine fibroids.

Imaging tests include

If results of either test are unclear, magnetic resonance imaging (MRI) is done. MRI can clearly show fibroids.

For hysteroscopy, a viewing tube is inserted through the vagina and cervix into the uterus. A local, regional, or general anesthetic is often used. During hysteroscopy, a sample of tissue may be removed and examined (biopsied).

Treatment of Fibroids

  • Drugs to relieve symptoms or shrink fibroids

  • Sometimes surgery to remove the entire uterus or only the fibroids

  • Sometimes procedures to destroy the fibroids

For most women who have fibroids but no bothersome symptoms or other problems, treatment is not required. They are reexamined every 6 to 12 months so that doctors can determine whether symptoms are worsening or lessening and whether fibroids are growing. Such periodic monitoring is sometimes called watchful waiting.

Several treatment options, including drugs and surgery, are available if bleeding or other symptoms worsen or if fibroids enlarge substantially.

Drugs for fibroids

A few drugs may be used to relieve symptoms or to shrink fibroids, but their effects are only temporary. No drug can permanently shrink a fibroid.

Rarely, if women have gone through menopause or are starting to go through it, a drug to shrink the fibroid may be used. But it may not be needed because fibroids may continue to shrink on their own after menopause.

The following drugs are commonly used:

  • Gonadotropin-releasing hormone agonists

  • Progestins

Gonadotropin-releasing hormone (GnRH) agonists (analogs) are most commonly used. These drugs are synthetic forms of a hormone produced by the body (GnRH). Leuprolide and goserelin are most commonly used. They can shrink fibroids and reduce bleeding by causing the body to produce less estrogen (and progesterone). Because they shrink the fibroids and reduce bleeding, doctors may give GnRH agonists before surgery to make removal of fibroids easier, reduce blood loss, and thus reduce the risks of surgery. The drugs may be injected once a month or implanted as a pellet under the skin. Nafarelin, another GnRH agonist, can be used as a nasal spray.

GnRH agonists are usually taken for less than 6 months. If taken for a long time, they may reduce bone density and increase the risk of osteoporosis Osteoporosis Osteoporosis is a condition in which a decrease in the density of bones weakens the bones, making breaks (fractures) likely. Aging, estrogen deficiency, low vitamin D or calcium intake, and... read more Osteoporosis . Low doses of estrogen, usually combined with a progestin (a drug that is similar to the hormone progesterone), may be given with GnRH agonists to help prevent loss of bone density.

Within 6 months after GnRH agonists are stopped, fibroids may become as large as they were before treatment.

Progestins Hormone Therapy for Menopause Menopause is the permanent end of menstrual periods and thus of fertility. For up to several years before and just after menopause, estrogen levels fluctuate widely, periods become irregular... read more Hormone Therapy for Menopause (such as medroxyprogesterone acetate or megestrol) can control bleeding in some women, but these drugs may not shrink fibroids as much as GnRH agonists. They reduce bleeding by preventing the lining of the uterus from growing too much. When the uterine lining grows too much, there is more of it to break down and be shed during menstruation. As a result, menstrual bleeding may be heavier than usual.

Progestins are taken by mouth. They may be taken every day or only for 10 to 14 consecutive days each menstrual cycle. Or doctors may give women injections of medroxyprogesterone acetate every 3 months or insert an intrauterine device (IUD Intrauterine Devices (IUDs) Intrauterine devices (IUDs) are small, flexible, T-shaped plastic devices that are inserted into the uterus. An IUD is left in place for 3, 5, 7, or 10 years, depending on the type, or until... read more Intrauterine Devices (IUDs) ) that releases a progestin called levonorgestrel. If taken by mouth every day, injected, or released by an IUD, progestins also provide contraception. However, these drugs may have bothersome side effects, such as weight gain, depression, and irregular bleeding.

Rarely, other drugs can be prescribed. They can be used if a GnRH agonist or progestin has been ineffective or has bothersome side effects. These drugs include

  • Mifepristone and related drugs (called antiprogestins): These drugs inhibit the activity of the hormone progesterone. As a result, the uterus and fibroids shrink.

  • Raloxifene and related drugs (called selective estrogen receptor modulators, or SERMs): These drugs reverse some of estrogen’s effects. They may not be as effective as other drugs.

  • Danazol (a synthetic hormone related to testosterone): Danazol inhibits the activity of estrogen and progesterone. It has many side effects, such as weight gain, acne, increased body hair (hirsutism), swollen ankles, loss of scalp hair, vaginal dryness, and lowering of the voice.

  • Tranexamic acid: This drug works by preventing blood clots (which are made by the body to help stop bleeding) from breaking down as quickly. As a result, bleeding decreases.

Nonsteroidal anti-inflammatory drugs (NSAIDs) may relieve pain but may not reduce bleeding.

Surgery for fibroids

Surgery is usually considered for women who have any of the following:

  • Fibroids that are rapidly enlarging

  • Bleeding that continues or recurs despite treatment with drugs

  • Severe or persistent pain

  • Large fibroids that cause problems, such as the need to urinate frequently, constipation, pain during sexual intercourse, or blockage of the urinary tract

  • For women who want to conceive, fibroids that have caused infertility or repeated miscarriages

If women do not want to have any more children or want a definitive cure, surgery may be a good option.

Several types of surgery can be done. Which one is recommended depends on the size, number, and location of fibroids. However, before making a decision about treatment, women should talk to their doctor about the problems that can result from each type of surgery so that they can make an informed decision.

Surgery to treat fibroids traditionally involves one of the following:

For hysterectomy, surgeons may use one of the following methods:

Laparoscopic surgery can be done with robotic assistance. The robot is a device used to control and manipulate surgical instruments inserted with the laparoscope. The laparoscope sends a three-dimensional image of the body's interior to a console. Surgeons sit at a console to view this image, and a computer translates their hand movements into precise movements of the surgical instruments.

For myomectomy, surgeons may use

  • Laparotomy

  • Laparoscopy

  • Hysteroscopy: Surgeons insert a telescope-like lighted device (hysteroscope) through the vagina into the uterus. Using instruments inserted through this tube, surgeons can cut tissue and remove fibroids on the inside of the uterus.

Laparoscopy and hysteroscopy are outpatient procedures, and recovery is faster than recovery after laparotomy. However, sometimes removing fibroids using laparoscopy or hysteroscopy may be difficult or impossible—for example, when there are many fibroids, when they are very large, or when they are embedded deeply in the wall of the uterus. In such cases, doctors do a laparotomy.

Hysterectomy may be preferred to myomectomy or may be required for several reasons:

A procedure called morcellation is often done during myomectomy or hysterectomy. For this procedure, surgeons cut the fibroids or uterine tissue into small pieces so that the pieces can be removed through a smaller incision. Very rarely, women with fibroids have cancer of the uterus Cancer of the Uterus The most common type of cancer of the uterus develops in the lining of the uterus (endometrium) and is called endometrial cancer. Endometrial cancer usually affects women after menopause. It... read more Cancer of the Uterus that is unsuspected and undiagnosed. If morcellation is done in such women, the cancer cells may be spread into the abdomen and pelvis. In such cases, cancer can develop in other locations unless a bag is used to catch all of the pieces of the fibroid, which are then removed from the body. When morcellation is done, such a bag must be used. Women should be informed of the very small risk of spreading cancerous cells if morcellation is done.

Other treatments for fibroids

Other treatments can be used to destroy rather than remove fibroids. These treatments may relieve symptoms, but how long symptom relief lasts has not been determined. These procedures include

  • Uterine artery embolization

  • High-intensity focused ultrasonography

  • Radiofrequency ablation

  • Cryoablation

  • Magnetic resonance-guided focused ultrasonography

After having one of these procedures, women should not become pregnant. Whether pregnancy after these procedures is safe is unclear.

For uterine artery embolization, doctors use an anesthetic to numb a small area of the thigh and make a small puncture hole or incision there. Then, they insert a thin, flexible tube (catheter) through the incision into the main artery of the thigh (femoral artery). The catheter is threaded to the arteries that supply blood to the fibroid, and small synthetic particles are injected. The particles travel to the small arteries supplying the fibroid and block them. As a result, the fibroid dies, then shrinks. Most of the rest of the uterus appears to be unaffected. However, whether the fibroid will regrow (because blocked arteries reopen or new arteries form) is unknown.

After uterine artery embolization, most women have pain and cramping in the pelvis, nausea, vomiting, fever, fatigue, and muscle aches. These symptoms develop within 48 hours after the procedure and gradually lessen over 7 days. An infection may develop in the uterus or surrounding tissues. Women recover more quickly after this procedure than after a hysterectomy or myomectomy, but they tend to have more complications and more return visits to the doctor. If fibroids continue to be a problem or grow back after embolization, hysterectomy is recommended.

Ultrasound-guided high-intensity focused sonography and magnetic resonance-guided focused ultrasonography use sound waves to destroy fibroids.

In radiofrequency ablation, doctors insert a needle that transmits an electrical current or heat into the fibroid and use it to destroy the core of the fibroid.

In cryoablation, a cold probe is used to destroy the fibroid.

Ultrasonography or magnetic resonance imaging may be used with radiofrequency ablation or cryoablation to locate the fibroids.

After these treatments, fibroids may grow back. In such cases, another treatment or a hysterectomy may be recommended.

Choice of treatment for fibroids

Choice of treatment for fibroids depends on the woman's situation, but doctors may use the following general guidelines:

  • If the fibroids do not cause any symptoms: No treatment

  • If the woman is going through or has passed through menopause: Watchful waiting (because symptoms tend to lessen as fibroids decrease in size after menopause)

  • If fibroids cause symptoms, particularly if the woman wants to become pregnant: A procedure that destroys rather than removes fibroids (such as uterine artery embolization or high-intensity focused sonography) or myomectomy

  • If symptoms are severe and other treatments are ineffective, particularly if the woman does not want to become pregnant: Hysterectomy, possibly preceded by treatment by drugs (such as GnRH agonists)

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