An ovarian cyst is a sac filled with fluid that forms on or inside of an ovary.

This article is about cysts that form during your monthly menstrual cycle, called functional cysts. Functional cysts are not the same as cysts caused by cancer or other diseases.

For more information about other causes of cysts on or near the ovaries, see also:

• Dermoid cyst
• Ectopic pregnancy
• Endometriosis
• Ovarian cancer
• Polycystic ovary syndrome

Physiologic ovarian cysts; Functional ovarian cysts; Corpus luteum cysts; Follicular cysts

Each month during your menstrual cycle, a follicle grows on your ovary.  A follicle is where an egg is developing. Most months, an egg is released from this follicle. This is called ovulation. If the follicle fails to break open and release an egg, the fluid stays in the follicle and forms a cyst. This is called a follicular cyst.

Another type of cyst occurs after an egg has been released from a follicle. This is called a corpus luteum cyst. Such cysts often contain a small amount of blood.

Ovarian cysts are more common from puberty to menopause. This period of time is known as the childbearing years. Ovarian cysts are less common after menopause.

Taking fertility drugs can cause a condition in which multiple large cysts are formed on the ovaries. This is called ovarian hyperstimulation syndrome. The cysts usually go away after a woman's period, or after a pregnancy.

Functional ovarian cysts are not the same as ovarian tumors (including ovarian cancer) or cysts due to hormone-related conditions such as polycystic ovary syndrome.

Ovarian cysts often cause no symptoms. When symptoms occur, they are typically pain or a late period.

An ovarian cyst is more likely to cause pain if it:

• Becomes large
• Bleeds
• Breaks open
• Interferes with the blood supply to the ovary
• Is bumped during sexual intercourse
• Is twisted or causes twisting (torsion) of the Fallopian tube

Symptoms of ovarian cysts can include:

• Bloating or swelling in the abdomen
• Pain during bowel movements
• Pain in the pelvis shortly before or after beginning a menstrual period
• Pain with intercourse or pelvic pain during movement
• Pelvic pain -- constant, dull aching
• Sudden and severe pelvic pain, often with nausea and vomiting, may be a sign of torsion or twisting of the ovary on its blood supply, or rupture of a cyst with internal bleeding

Changes in menstrual periods are not common with follicular cysts, and are more common with corpus luteum cysts. Spotting or bleeding may occur with some cysts.

Your doctor or nurse may discover a cyst during a pelvic exam, or when you have an ultrasound test for another reason.

Ultrasound may be done to diagnose a cyst. Your doctor or nurse may want to check you again in 6 weeks to make sure it is gone.

Other imaging tests that may be done when needed include:

• CT scan
• Doppler flow studies
• MRI

The following blood tests may be done:

• Ca-125 test, to look for possible cancer if you have an abnormal ultrasound or are in menopause
• Hormone levels (such as LH, FSH, estradiol, and testosterone)
• Pregnancy test (Serum HCG)

Functional ovarian cysts often don't need treatment. They usually go away on their own within 8 - 12 weeks.

If you have frequent cysts, your doctor or nurse may prescribe birth control pills (oral contraceptives). These medicines may reduce the risk of new ovarian cysts. Birth control pills do not decrease the size of current cysts.

Surgery to remove the cyst or ovary may be needed to make sure it isn't ovarian cancer. Surgery is more likely to be needed for:

• Complex ovarian cysts that don't go away
• Cysts that are causing symptoms and do not go away
• Simple ovarian cysts that are larger than 5 - 10 centimeters
• Women who are menopausal or near menopause

Types of surgery for ovarian cysts include:

• Exploratory laparotomy
• Pelvic laparoscopy to remove the cyst or the ovary

Other treatments may be recommend if you have polycystic ovary syndrome or another disorder that can cause cysts.

Cysts in women who are still having periods are more likely to go away. There is a higher risk of cancer in women who are postmenopausal.

Complications have to do with the condition causing the cysts. Complications can occur with cysts that:

• Bleed
• Break open
• Show signs of changes that could be cancer
• Twist

Call for an appointment with your health care provider if:

• You have symptoms of an ovarian cyst
• You have severe pain
• You have bleeding that is not normal for you

Also call for an appointment if the following symptoms have been present on most days for at least 2 weeks:

• Getting full quickly when eating
• Losing your appetite
• Losing weight without trying

If you are not trying to get pregnant and you often get functional cysts, you can prevent them by taking hormone medications (such as birth control pills), which prevent follicles from growing.

Katz VL. Benign gynecologic lesions: Vulva, vagina, cervix, uterus, oviduct, ovary. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 18.

Bulun SE. The physiology and pathology of the femalereproductive axis. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 17.