A fibroid is a noncancerous tumor composed of muscle and fibrous tissue.
Fibroids are also called leiomyomas or myomas.
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 have fibroids that cause symptoms. Fibroids are more common among women who are overweight.
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. They may grow in different parts of the uterus, usually in the wall (which has three layers):
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.
|Where Fibroids Grow
Fibroids can grow in different parts of the uterus:
In the wall of the uterus (intramural fibroid)
Under the lining of the uterus (submucosal fibroid)
On the outside of the uterus (subserosal fibroid)
Some fibroids grow on a stalk. They are called pedunculated fibroids.
Symptoms depend on the number of fibroids, their size, and 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 miscarriage, early (preterm) labor, abnormal positioning (presentation) of the baby before delivery, and excessive blood loss after delivery (postpartum hemorrhage).
Fibroids can cause 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.
Doctors may suspect fibroids based on results of a pelvic examination. However, imaging tests are often needed to confirm the diagnosis.
Imaging tests include
If results of either test are unclear, magnetic resonance imaging (MRI) is done. MRI can clearly show fibroids.
If women have had any bleeding other than that during their menstrual periods, doctors may want to exclude cancer of the uterus. So they may do a Papanicolaou (Pap) test, a biopsy of the uterine lining (endometrial biopsy), ultrasonography, sonohysterography, or hysteroscopy. 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 (biopsy).
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.
Several treatment options, including drugs and surgery, are available if bleeding or other symptoms worsen or if fibroids enlarge substantially.
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 the only treatment needed because fibroids may continue to shrink on their own after menopause.
Gonadotropin-releasing hormone (GnRH) analogs (agonists—see see Drugs) 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 analogs 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 analog, can be used as a nasal spray. GnRH analogs 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. Low doses of estrogen, usually combined with a progestin (a drug that is similar to the hormone progesterone), may be given with GnRH analogs to help prevent loss of bone density. Within 6 months after GnRH analogs are stopped, fibroids may become as large as they were before treatment.
Progestins (such as medroxyprogesterone acetate or megestrol) can control bleeding in some women. 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. 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) that releases this drug. If taken by mouth every day or injected, 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 analog or progestin has been ineffective or has bothersome side effects. These drugs include
Nonsteroidal anti-inflammatory drugs (NSAIDs) may relieve pain but may not reduce bleeding.
Surgery is usually considered for women who have any of the following:
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
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:
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
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 this procedure, 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.
Some procedures (high-intensity focused sonography, radiofrequency ablation, and magnetic resonance-guided focused ultrasound surgery) use heat to destroy fibroids. For these procedures, 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 another procedure (cryoablation), a cold probe is used to destroy the fibroid. Ultrasonography or magnetic resonance imaging may be used with these procedures to locate the fibroids.
After these treatments, fibroids may grow back. In such cases, another treatment or a hysterectomy may be recommended.
Last full review/revision September 2013 by David G. Mutch, MD; Scott W. Biest, MD