Uterine fibroids (leiomyomata, singular leiomyoma) are the most common neoplasm in females, and may affect about 25 % of white and 50% of black women during the reproductive years. Fibroids may be removed simply by means of a hysterectomy, but much more favourably by a myomectomy or by uterine artery embolization, which preserve the uterus. Fibroids, particularly when small, may be entirely asymptomatic. Generally, symptoms relate to the location of the lesion and its size. Important symptoms include abnormal gynecologic hemorrhage, pain, urinary frequency or retention, and in some cases, infertility. During pregnancy they may be the cause of miscarriage, bleeding, premature labor, or interference with the position of the fetus. Very few lesions are or become malignant. Signs that a fibroid may be malignant are rapid growth or growth after menopause.