Ovarian cysts are fluid-filled sacs that develop on one or both ovaries. Typically, ovarian cysts are not cancerous—although they may cause similar symptoms, such as pelvic pain, a feeling of pressure in the abdomen and difficulty emptying the bladder. Cysts often develop with a woman’s menstrual cycle during her reproductive years. Post-menopausal women with ovarian cysts have a higher risk of cancer.