Uterine polyps are either benign, precancerous or cancerous, and benign uterine polyps do not always become cancerous, according to Mayo Clinic. A woman can have a single polyp or several polyps ranging in size from a few millimeters to several centimeters, and most are benign.
Uterine polyps are also called endometrial polyps because they grow in the endometrium, or the inner lining of the uterus. Symptoms of uterine polyps include irregular menstrual periods, unusually heavy flow during periods, vaginal spotting or bleeding after menopause, and infertility, according to the Cleveland Clinic. Uterine polyps most commonly occur in women between ages 40 and 50, possibly due to changes in hormone levels, especially estrogen levels, caused by menopause.