Uterine fibroids are benign tumors in the uterus. They are composed of the same smooth muscle fibers as the uterine wall (myometrium) but are much denser than normal myometrium. This condition affects approximately 20 to 40 percent of premenopausal women, but only 5 to 10 percent of premenopausal women actually develop symptoms due to fibroids.
Unlike other tumors, these benign growths do not commonly spread to other regions of the body and are not typically dangerous. Developing fibroids are more prevalent in women who are overweight, African-American, over the age of 40, have high blood pressure, do not have children, or have first-degree relatives with fibroids. The diagnosis is typically confirmed by transvaginal ultrasound or magnetic resonance imaging (MRI) of the pelvis.