A uterine fibroid is a noncancerous growth in the wall of the uterus. A fibroid can be any size from microscopic to as large as a cantaloupe.
Fibroids are firm, round lumps, made of muscle, that often occur in groups in the uterine wall. Fibroids usually grow very slowly in the wall of the uterus. They grow bigger in response to increased levels of estrogen, one of the female hormones.
Some conditions cause increased estrogen levels and thus contribute to the growth of fibroids. These conditions include: hormone replacement therapy for menopauseoral contraceptives, or birth control pillspregnancy
After menopause, fibroids may shrink or disappear completely.
Most women have no symptoms with uterine fibroids. Symptoms depend on the number, size, and location of fibroids. Some of the common symptoms are as follows: heavy or prolonged menstruationanemia, a low red blood cell count, from heavy bleedingbleeding between periodsdyspareunia, or painful intercoursefrequent urination, caused by tumor pressure on the bladderpain or pressure in the lower abdomen or lower back
No clear cause of uterine fibroids is known. Research indicates that fibroids may grow bigger in response to estrogen and progesterone, but these hormones do not cause the fibroids to form in the first place. Fibroids are diagnosed in black women two to three times more often than in white women.
Since the cause of uterine fibroids is not yet known, no way is known to prevent them.
Fibroids are very common, especially in women older than 35 years of age. They rarely become malignant (cancerous). Fibroids that grow near the outer surface of the uterus can be felt as lumps during a pelvic exam. Fibroids growing in the lining of the uterus may be harder to detect during a pelvic exam. The diagnosis can be confirmed by an ultrasound exam. A hysteroscopy, in which a fiberoptic tube is used to examine the inside of the uterus, may also be done.
Fibroids can make it difficult to conceive a baby. During pregnancy, a fibroid can cause a miscarriage or difficulty with delivery. A fibroid can also become twisted and need emergency surgery. Although rare, cancerous fibroids do occur.
Fibroids are not contagious. A fibroid may pose a risk to the unborn child during pregnancy.
Most fibroids do not cause symptoms and need no treatment. Sometimes, medicines are used to shrink the tumor by decreasing the level of estrogen in the blood. This is only a temporary solution, since the fibroids regrow when the medication is stopped.
Women with symptoms like heavy bleeding and pain may need surgery. If the woman is not planning to have any more children, a hysterectomy, that is, surgical removal of the uterus, may be recommended. If the woman would like to become pregnant in the future, a myomectomy may be done instead. This is surgery to remove only the fibroid. The uterus is left intact.
Another procedure that may be performed is an arterial embolization. A tube is threaded into a uterine artery. Small beads are injected into the artery leading to the tumor. This blocks the blood flow to the artery, shrinking the fibroid. MRI-guided focused ultrasound treatment is a new procedure. It applies an ultrasound externally and focuses the energy on the fibroid to destroy it. Laser treatment, called myolysis, is another procedure used to destroy fibroids.
Surgery can be complicated by bleeding, infection, or reactions to anesthesia.
If a hysterectomy was done, no more fibroids can develop. If the ovaries were removed along with the uterus, hormone replacement therapy may be necessary. Fibroids grow back about 10% of the time after a myomectomy.
Women with fibroids should be examined every 6-12 months to monitor the size of the fibroid. Any unusual symptoms or concerns should be reported to the healthcare professional.
Mayo Family Health Book, DE Larson, 1996.
Understanding Your Body, F Stewart et al, 1987.
Merck Manual of Medical Information, 1997.