Uterine leiomyomata (fibroids) are a common benign tumor of the uterine muscle in premenopausal women. These tumors may cause bleeding, pelvic pain and pressure. Because fibroids grow in the presence of estrogen, medical therapies that decrease estrogen levels (like GnRH analog) cause fibroids to shrink and so may relieve symptoms. However, such medication can only be given short-term and has inconvenient side effects such as hot-flushes. Thus, many women with symptomatic fibroids choose to have them removed surgically, either individually or by removing the uterus via hysterectomy.