Ovarian Cyst
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).
Ovarian cysts affect women in all ages. They occur most often, however, during a woman's child bearing 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 of Cysts
Functional cysts
Functional cysts or simple cysts are part of the normal process of menstruation. They have nothing to do with disease, and can be treated. 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.

Follicular cyst of ovary
Follicular cyst which is the most common type of ovarian cyst is the graafian follicle cyst or follicular cyst.

Lutein cysts
Corpus luteum cyst
Corpus luteum cyst, which may rupture about the time of menstruation and take up to three months to disappear entirely.
Theca lutein cyst
The term "hemorrhagic cyst" is used to describe cysts where significant quantities of blood have entered. "Hemorrhagic follicular cyst" is classified under N83.0 in ICD-10, and "hemorrhagic corpus luteum cyst" is classified under N83.1.

Non-functional cysts
There are several other conditions affecting the ovary that are described as types of cysts, but are not usually grouped with the functional cysts. (Some of these are more commonly or more properly known by other names.) These include:
Dermoid cyst
Chocolate cyst of ovary
An endometrioma, endometrioid cyst, endometrial cyst, or chocolate cyst is caused by endometriosis, and formed when a tiny patch of endometrial tissue (the mucous membrane that makes up the inner layer of the uterine wall) bleeds, sloughs off, becomes transplanted, and grows and enlarges inside the ovaries.
A polycystic-appearing ovary is diagnosed based on its enlarged size — usually twice normal —with small cysts present around the outside of the ovary. It can be found in "normal" women, and in women with endocrine disorders. An ultrasound is used to view the ovary in diagnosing the condition. Polycystic-appearing ovary is different from the polycystic ovarian syndrome, which includes other symptoms in addition to the presence of ovarian cysts.

Ovarian cyst Treatment
About 95% of ovarian cysts are benign, meaning they are not cancerous
Treatment for cysts depends on the size of the cyst and symptoms. For small, asymptomatic cysts, the wait and see approach with regular check-ups will most likely be recommended.
Pain caused by ovarian cysts may be treated with:
Pain relievers, including acetaminophen (Tylenol), nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin, Advil), or narcotic pain medicine (by prescription) may help reduce pelvic pain. NSAIDs usually work best when taken at the first signs of the pain.
A warm bath, or heating pad, or hot water bottle applied to the lower abdomen near the ovaries can relax tense muscles and relieve cramping, lessen discomfort, and stimulate circulation and healing in the ovaries. Bags of ice covered with towels can be used alternately as cold treatments to increase local circulation.
Combined methods of hormonal contraception such as the combined oral contraceptive pill -- the hormones in the pills may regulate the menstrual cycle, prevent the formation of follicles that can turn into cysts, and possibly shrink an existing cyst. (American College of Obstetricians and Gynecologists, 1999c; Mayo Clinic, 2002e)
Cysts that persist beyond two or three menstrual cycles, or occur in post-menopausal women, may indicate more serious disease and should be investigated through ultrasonography and laparoscopy, especially in cases where family members have had ovarian cancer. Such cysts may require surgical biopsy. Additionally, a blood test may be taken before surgery to check for elevated CA-125, a tumor marker, which is often found in increased levels in ovarian cancer, although it can also be elevated by other conditions resulting in a large number of false positives.
For more serious cases where cysts are large and persisting, doctors may suggest surgery. Some surgeries can be performed to successfully remove the cyst(s) without hurting the ovaries, while others may require removal of one or both ovaries.