Uterine fibroids

Definition

Uterine fibroids are non-cancerous tumors that develop within or attach to the wall of the uterus, a female reproductive organ.

Alternative Names

Causes

Uterine fibroids are the most common pelvic tumor.

The cause of uterine fibroid tumors is unknown. Oral contraceptives and pregnancy lower the risk of developing new fibroid tumors.

Fibroids may be present in 15 - 20% of women in their reproductive years -- the time after starting menstruation for the first time and before menopause. Fibroids may affect 30 - 40% of women over age 30. Fibroids occur 2 to 3 times more frequently in African-American women than in Caucasian women.

The growth of a fibroid seems to depend on the hormone estrogen. As long as a woman with fibroids is menstruating, the fibroids will probably continue to grow, usually slowly.

Fibroids rarely affect females younger than 20 or who are postmenopausal.

Fibroids begin as small seedlings that spread throughout the muscular walls of the uterus. They can be so tiny that you need a microscope to see them. However, they can also grow very big. They may fill the entire uterus, and may weigh several pounds. Although it is possible for just one fibroid to develop, usually there is more than one. 

Sometimes, a fibroid hangs from a long stalk, which is attached to the outside of the uterus. Such a fibroid is called a pedunculated fibroid. It can become twisted and cause a kink in blood vessels feeding the tumor. This type of fibroid may require surgery.

References

L Speroff, M Fitz. Clinical Gynecologic Endocrinology and Infertility. 7th ed. Lippincott Williams & Wilkins; 2004.

Casini ML, Rossi F, Agostini R, Unfer V. Effects of the position of fibroids on fertility. Gynecol Endocrinol. 2006 Feb;22(2):106-9.