Causes of Uterine Fibroids

Doctors are not certain of the exact causes of uterine fibroids, but they suggest several possible factors. Hormones, the environment and genes all seem to play a role. Other chemicals--such as an insulin-like growth factor--might also affect the growth of fibroids. Doctors do know that the hormones estrogen and progesterone affect fibroid growth. During pregnancy when hormones are high, fibroids grow rapidly. The fibroids stop growing or shrink when a woman uses anti-hormone medication or when she reaches menopause. Almost all uterine fibroids are benign or noncancerous.

Causes

• Researchers believe that a combination of genes (fibroids seem to be hereditary), the environment, and hormones (such as estrogen levels) lead to the development of uterine fibroids. Age seems to play a role too. About 40 % of women have developed fibroids by age 40 and they are present in 70 to 80 % of women over age 50. Uterine fibroids are more prevalent among African American women than among other races and among women who are overweight. In a 2002 study, National Institutes of Health researchers identified 145 genes related to the development of uterine fibroids. This study also revealed that the susceptibility to develop uterine fibroids is passed from father to daughter.

Symptoms

• Some women do not have any symptoms with uterine fibroids. For those who have symptoms, they can include heavy menstrual bleeding, longer-than-normal menstrual periods or bleeding between periods, pain or pressure in the pelvis area, urinary incontinence or frequent urination, constipation, pain during intercourse, complications during pregnancy and labor, and leg or back pain. On rare occasions, uterine fibroids can cause reproductive problems or acute pain.

Types

• Uterine fibroids are described based on the location where they grow. Submucosal fibroids grow inside the uterus. Subserosal fibroids grow outside of the uterus. Intramural fibroids grow within the uterus wall. There can also be fibroids that grow on stalks that are attached to the surface of the uterus or the cavity of the uterus. In appearance, they look like mushrooms. These fibroids are called pedunculated fibroids.

Size

• Uterine fibroids grow from the smooth uterine tissue called the myometrium. From a single cell that reproduces over and over, a mass grows. This mass is pale, rubbery in texture and firm; it is different from the uterine tissue around it. Uterine fibroids can be as small as seedlings that cannot be seen by the human eye. They can also be large masses that cause the uterus to be distorted and enlarged. There can be a single fibroid or multiple fibroids.

Diagnosis

• Doctors can usually determine whether a woman has uterine fibroids when the regular pelvic exam is performed. Follow-up imaging tests can then be performed to produce a "picture" and confirm the diagnosis. These include ultrasound, which uses sound waves; magnetic resonance imaging, which uses magnets and radio waves; cat scan, which takes X-ray images from different angles; hysterosalpingogram, which involves injecting X-ray dye; or sonohysterogram, which involves injecting water and making ultrasound pictures.

Treatment

• There are many treatments available for uterine fibroids. Sometimes the treatment is simply to watch and wait, with a doctor monitoring the fibroid to see how it grows. Other common treatments include medications or surgery. The medications can help a woman deal with the discomfort or they can regulate the menstrual cycle, which can help shrink the fibroids. There are several surgical options including hysterectomy, myomectomy, uterine artery embolization, or focused ultrasound surgery.