Most ovarian cysts are never noticed and resolve without women ever realizing that they are there. When a cyst causes symptoms, pain in the belly or pelvis is by far the most common one. What is a functional ovarian cyst? There are usually two types of functional cysts, one called a follicle cyst the other a corpus luteum cyst. The cysts are called functional because they are normal but can develop into problems of pain, bleeding and missed periods. They are different from cancer and other ovarian tumors.