A uterine fibroid (leiomyoma) is a common, usually non-cancerous growth of smooth muscle and fibrous tissue in or on the wall of the uterus. Fibroids are very common in the reproductive years and are influenced by estrogen and progesterone, so they often shrink after menopause.
Many fibroids cause no symptoms. When they do, it depends largely on their size and location — common issues include heavy or prolonged periods (a cause of heavy menstrual bleeding and anemia), pelvic pressure, and frequent urination. See uterine fibroids. They are different from adenomyosis.