Your Monthly Cycle
One of the two ovaries — each about the size of a walnut — produces an egg every month during your menstrual cycle. An egg, encased in a sac called a follicle, grows inside the ovary. On about day 5 of your menstrual cycle, the hormone estrogen signals the endometrium (the lining of the uterus) to grow and thicken to prepare for a possible pregnancy. About day 14, the egg is released from the ovary. This is called ovulation.

After ovulation, the empty follicle becomes the corpus luteum, which remains until the next period.

Types of Ovarian Cysts
Ovarian cysts are quite common in women during their childbearing years. Most cysts result from the changes in hormone levels that occur during the menstrual cycle and the production and release of eggs from the ovaries. A woman can develop one cyst or many cysts.

There are different types of ovarian cysts, and each type causes a variety of symptoms.

Functional Cysts
The most common type of ovarian cyst is called a functional cyst. There are two types of functional cysts — follicle and corpus luteum. Both of these cysts usually have no symptoms or minor ones when they occur. They disappear within a few months.

Dermoid Cysts
Dermoid cysts are made up of different kinds of tissue, such as skin, hair, fat and teeth.

Cystadenomas
Cystadenomas are cysts that develop from cells on the outer surface of the ovary. They are usually benign, but they can create problems.

Endometriomas
Endometriomas are cysts that form when endometrial tissue grows in the ovaries. An endometrioma is also known as a "chocolate cyst" because it is filled with dark, reddish-brown blood.

An endometrioma is often linked to a condition known as endometriosis.

Multiple Cysts
Women who do not ovulate regularly can develop multiple cysts. It can be linked to a condition called polycystic ovary syndrome (PCOS).

Symptoms
Most ovarian cysts are small and do not cause symptoms. Some go away on their own. Some may cause symptoms because of twisting, bleeding and rupture.

Some cysts may be cancer. The risk of ovarian cancer increases as you get older.

Diagnosis
An ovarian cyst is often found during a routine pelvic exam. When your doctor detects an enlarged ovary, he or she may do other tests to confirm the diagnosis:

• Ultrasound
• Laparoscopy
• Blood tests

Some of these tests provide further information about the cyst that is helpful in planning treatment. Some may be used only if there is a high risk of problems.

Treatment
If your cyst is not causing any symptoms, your doctor may simply monitor it for one to two months. Most functional cysts go away on their own over one or two menstrual cycles.

If your cyst is large or causing symptoms, your doctor may suggest treatment with hormones or surgery.

Hormonal Therapy
Your doctor may prescribe oral contraceptives (birth control pills) to treat functional ovarian cysts.

Surgery
Your doctor may suggest surgery to remove the cyst. Sometimes, a cyst can be removed while leaving the ovary — called cystectomy. In other cases, one or both of the ovaries may have to be removed.

Finally …
Ovarian cysts are common in women during their childbearing years. Although most cysts are harmless and go away on their own, your doctor will want to keep track of any cyst to be sure that it does not grow and cause problems.

This excerpt from ACOG's Patient Education Pamphlet is provided for your information. It is not medical advice and should not be relied upon as a substitute for visiting your doctor. If you need medical care, have any questions, or wish to receive the full text of this Patient Education Pamphlet, please contact your obstetrician-gynecologist.