Uterine fibroids

Alternative names
Leiomyoma; Fibromyoma; Myoma; Fibroids

Uterine fibroids are benign tumors of muscle and connective tissue that develop within, or are attached to, the uterine wall.

Causes, incidence, and risk factors

The cause of fibroid tumors of the uterus is unknown. However, it is suggested that fibroids may enlarge with estrogen therapy (such as oral contraceptives) or with pregnancy.

Fibroid growth seems to depend on regular estrogen stimulation, rarely affecting women younger than 20 or postmenopausal women. As long as a woman with fibroids is menstruating, the fibroids will probably continue to grow, although growth is usually quite slow.

Fibroids can be microscopic, but they can also grow to fill the uterine cavity, and may weigh several pounds. Uterine fibroids are the most common pelvic tumor and they may be present in 15 to 20% of reproductive-age women, and 30 to 40% of women over 30.

Fibroids occur 3 to 9 times more frequently in African-American women than in Caucasian women.

Although it is possible for a single fibroid to develop, usually there are a number of them, which begin as small seedlings spread throughout the muscular walls of the uterus.

They slowly enlarge and become more nodular, frequently intruding into the cavity of the uterus or growing out beyond the normal boundary of the uterus. Rarely, a fibroid will hang from a long stalk attached to the outside of the uterus. This is called a pedunculated fibroid, and it may twist and cause the blood vessels feeding the tumor to kink. Hospitalization and surgery may be needed in this instance


  • Sensation of fullness or pressure in lower abdomen  
  • Pelvic cramping or pain with periods  
  • Abdominal fullness, gas  
  • Increase in urinary frequency  
  • Heavy menstrual bleeding (menorrhagia), sometimes with the passage of blood clots  
  • Sudden, severe pain due to a pedunculated fibroid

Note: There are often no symptoms.

Signs and tests

A pelvic examination reveals an irregularly shaped, lumpy, or enlarged uterus. Frequently, this diagnosis is reliable. However, on occasion, diagnosis is difficult, especially in obese women. Fibroid tumors have been mistaken for ovarian tumors, inflammatory processes of the tubes, and pregnancy.

A transvaginal ultrasound or pelvic ultrasound may be performed to confirm the findings.

A D and C procedure or a pelvic laparoscopy may be necessary to rule out other, potentially malignant, conditions.


Methods of treatment depend on the severity of symptoms, the patient’s age, her pregnancy status, her possible desire for future pregnancies, her general health, and characteristics of the fibroids. Treatment may consist of simply monitoring the rate of growth of the fibroids with periodic pelvic exams or ultrasound.

Nonsteroidal anti-inflammatory medications like ibuprofen or naprosyn may be recommended for lower abdominal cramping or pain with menses. Iron supplementation will help to prevent anemia in women with heavy periods. These methods are usually sufficient in premenopausal women.

Hormonal treatment, involving drugs such as injectable Depo Leuprolide, causes fibroids to shrink, but can also cause significant side effects. This method is sometimes used for short treatment periods before surgical procedures or when menopause is imminent.

The hormones produce an environment in the body that is very similar to that of menopause, with associated side effects like hot flashes, vaginal dryness, and loss of bone density.

The treatment lasts several months and during this time the reduction in estrogen concentration allows the fibroids to shrink. Fibroids will begin to enlarge as soon as treatment stops.

Hysteroscopic resection of fibroids (an outpatient surgical procedure) may be appropriate for women with fibroids growing within the uterine cavity. In this procedure, a small camera and instruments are inserted through the cervix into the uterus to remove the fibroid tumors.

Uterine artery embolization is a new procedure aimed at preventing the need for major surgery. Small catheters are placed through veins in the pelvis and advanced to the arteries that supply the uterus with blood.

Materials are then injected to block these arteries permanently. The decreased blood supply to the uterus may prevent further growth of the fibroids and may cause them to shrink. The long-term effects of this procedure are still unknown, and the safety of pregnancy after this procedure is questionable.

A myomectomy, which is a surgical procedure to remove just the fibroids, is frequently the chosen treatment for premenopausal women who want to bear more children, because it usually can preserve fertility.

Another advantage of a myomectomy is that it controls pain or excessive bleeding that some women with uterine fibroids experience. However, a myomectomy often cannot remove very small fibroids that may grow and cause symptoms in the future.

A total hysterectomy, which involves removal of the uterus, is a curative option that is often chosen by older women.

Expectations (prognosis)

Prior to menopause, fibroids are likely to grow slowly. Women with known fibroids who choose to have children may be advised to become pregnant in early adulthood.

As a general rule, fibroids don’t interfere with fertility. However, a tumor sometimes blocks the fallopian tubes and prevents sperm from reaching and fertilizing eggs. In some cases, fibroids may prevent a fertilized egg from implanting in the uterine lining. However, proper treatment may restore fertility.

After a pregnancy is established, existing fibroids may grow due to the increased blood flow and estrogen levels. These usually return to their original size after the baby has been delivered.

Most women are able to carry their babies to term, but some of them end up delivering prematurely because there is not enough room in the uterus to sustain full term.

Cesarean section may be needed for delivery since fibroid tumors can occasionally block the birth canal or cause the baby to be positioned abnormally. After menopause, new fibroids rarely develop and those already present usually shrink.


Fibroids may cause infertility because they can interfere with conception or implantation. They may cause premature delivery because of decreased area within the uterus. Severe pain or excessively heavy bleeding with fibroids may necessitate emergency surgery.

Rarely, malignant changes may occur. These usually take place in postmenopausal women. The most common warning sign is rapid enlargement of a fibroid and definitive diagnosis is usually not made until the time of surgery.

Calling your health care provider
Call your health care provider if gradual changes in your menstrual pattern occur (heavier flow, increased cramping, bleeding between periods), or if fullness or heaviness develops in your lower abdomen. Frequently there is associated pressure or discomfort and occasionally interference with normal urination frequency.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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