What is an Ovarian Cyst?

DEAR ASK THE DOCTOR: My friend said her doctor told her that she has an Ovarian Cyst. What is this? I am very worried for her.

DEAR MOLLY: A cyst is a fluid-filled sac. They can form anywhere in the body. Ovarian cysts (sists) form in or on the ovaries.  Ovarian cysts are small fluid-filled sacs that develop in a woman's ovaries. Most cysts are harmless, but some may cause problems such as rupturing, bleeding, or pain; and surgery may be required to remove the cyst(s).

The most common type of ovarian cyst is a functional cyst.  Functional cysts often form during the menstrual cycle. The two types are:

* Follicle cysts - These cysts form when the sac doesn't break open to release the egg. Then the sac keeps growing. This type of cyst most often goes away in 1 to 3 months.

* Corpus luteum cysts - These cysts form if the sac doesn't dissolve. Instead, the sac seals off after the egg is released. Then fluid builds up inside. Most of these cysts go away after a few weeks. They can grow to almost 4 inches. They may bleed or twist the ovary and cause pain. They are rarely cancerous. Some drugs used to cause ovulation, such as Clomid® or Serophene®, can raise the risk of getting these cysts.

Other types of ovarian cysts are:

* Endometriomas (EN-doh-MEE-tree-OH-muhs) - These cysts form in women who have endometriosis (EN-doh-MEE-tree-OH-suhss). This problem occurs when tissue that looks and acts like the lining of the uterus grows outside the uterus. The tissue may attach to the ovary and form a growth. These cysts can be painful during sex and during your period.

* Cystadenomas (siss-tahd-uh-NOH-muhs) - These cysts form from cells on the outer surface of the ovary. They are often filled with a watery fluid or thick, sticky gel. They can become large and cause pain.

* Dermoid (DUR-moid) - These cysts contain many types of cells. They may be filled with hair, teeth, and other tissues that become part of the cyst. They can become large and cause pain.

* Polycystic (pol-ee-SISS-tik) - These cysts are caused when eggs mature within the sacs but are not released. The cycle then repeats. The sacs continue to grow and many cysts form. For more information about polycystic ovaries, refer to our FAQ about Polycystic Ovary Syndrome.