Fibroids are the most frequently seen tumors of the female reproductive system. Also known as uterine myomas, leiomyomas, or fibromas, they are firm, compact tumors that are made of smooth muscle cells and fibrous connective tissue that develop in the uterus. In more than 99% of cases they are benign (non-cancerous). They may range in size from the size of a pea to the size of a softball or small grapefruit. Some women never have symptoms, the most common of which are: heavy or prolonged menstrual periods; abnormal bleeding between menstrual periods; pelvic pain; frequent urination; low back pain; pain during intercourse; a firm mass, often located near the middle of the pelvis, which can be felt by a physician.