An ovarian cyst is any collection of fluid, surrounded by a very thin wall, within an ovary. Any ovarian follicle that is larger than about two centimeters is termed an ovarian cyst. An ovarian cyst can be as small as a pea, or larger than an orange.

Most ovarian cysts are functional in nature, and harmless (benign). In the US, ovarian cysts are found in nearly all premenopausal women, and in up to 14.8% of postmenopausal women.

Ovarian cysts affect women of all ages. They occur most often, however, during a woman's
childbearing years.

Some ovarian cysts cause problems, such as bleeding and pain. Surgery may be required to remove cysts larger than 5 centimeters in diameter.

Classification

Functional cysts

Some, called functional cysts, or simple cysts, are part of the normal process of menstruation. They have nothing to do with disease, and can be treated. There are 3 types, Graafian, Luteal, and Hemorrhagic. These types of cysts occur during ovulation. If the egg is not released, the ovary can fill up with fluid. Usually these types of cysts will go away after a few period cycles.

Graafian follicle cyst