Ovarian cysts are fluid-filled, sac-like structures within an ovary. They can form for numerous reasons. The most common type is a follicular cyst, which results from the growth of a follicle. A follicle is the normal fluid-filled sac that contains an egg. Follicular cysts form when the follicle grows larger than normal during the menstrual cycle and does not open to release the egg. Usually, follicular cysts resolve on their own over the course of days to months. Cysts can contain blood (hemorrhagic or endometrioid cysts) from injury or leakage of tiny blood vessels into the egg sac. Occasionally, the tissues of the ovary develop abnormally to form other body tissues such as hair or teeth. Cysts with these abnormal tissues are called dermoid cysts.

Most 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. The pain can be caused from rupture of the cyst, rapid growth and stretching, bleeding into the cyst, or twisting of the cyst around its blood supply. In order to diagnose a cyst an ultrasound must be performed. Ultrasound is an imaging method that uses sound waves to produce an image of structures within the body. Ultrasound imaging is painless and causes no harm.

Cysts can also be detected with other imaging methods, such as CAT scan or MRI scan (magnetic resonance imaging).

Most ovarian cysts in women of childbearing age are follicular cysts (functional cysts) that disappear naturally in 1-3 months. Although they can rupture (usually without ill effects), they rarely cause symptoms. They are benign and have no real medical consequence. They may be diagnosed coincidentally during a pelvic examination in women who do not have any related symptoms. All women have follicular cysts at some point that generally go unnoticed.

A follicular cyst in a woman of childbearing age is usually observed for a few menstrual cycles because the cysts are common, and ovarian cancer is rare in this age group. Sometimes ovarian cysts in menstruating women contain some blood, called hemorrhagic cysts, which frequently resolve quickly.

The ideal treatment of ovarian cysts depends on the woman’s age, the size (and change of size) of the cyst, and the cyst’s appearance on ultrasound.

Treatment can consist of simple observation, or it can involve evaluating blood tests such as a CA-125 to help determine the potential for cancer (keeping in mind the many limitations of CA-125 testing described above).

The tumor can be removed either with laparoscopy, or if needed, an open laparotomy (using and incision at the bikini line) if it is causing severe pain, not resolving, or if it is suspicious in any way. Once the cyst is removed, the growth is sent to a pathologist who examines the tissue under a microscope to make the final diagnosis as to the type of cyst present.