An ovarian cyst is a fluid-filled sac in or on the ovary. Most ovarian cysts are noncancerous cysts that occur as a result of ovulation. These are called functional cysts and normally disappear without any medical intervention, usually in about 1 to 3 months. Often functional cysts do not cause any symptoms but other times they can cause abdominal pain, menstrual irregularities, nausea and vomiting. Some cysts, however, are "tumors" meaning that the mass in the ovary is not a normal finding. These can be benign or malignant and usually require surgery as part of treatment. 97% of ovarian masses are "cysts" that occur and regress naturally.
Most cysts that develop in women in the childbearing age are a function of their "working" ovaries. A girl starts puberty with about 400,000 egg-producing follicles in her ovaries. Each month hundreds of these follicles attempt to develop, fail to do so and die. Only one succeeds, enlarges, produces estrogen and secretes fluid that surrounds the egg, then breaks open and releases the egg into the fallopian tube during ovulation. Once its egg is extruded, the follicle continues to function for the next two weeks as a corpus luteum secreting both estrogen and progesterone. In the absence of pregnancy, the corpus luteum collapses. Hence, each month that a woman ovulates, a small ovarian cyst is formed; this usually measures 1.5 to 2 cm. Prior to ovulation, the follicle may accumulate too much fluid and form a cyst that is greater than three cm. After ovulation, the corpus luteum can bleed into itself and also enlarge, forming a hemorrhagic cyst.
There are, of course, cysts that are not functional. They remain and continue to grow. Age is a factor for both symptoms and diagnosis. Blood-filled cysts in women of reproductive age may be due to endometriosis. Endometrial-like cells that are normally part of the lining of the uterus attach themselves or develop on the wrong surfaces in the pelvis like the ovaries, the pelvic wall, bladder, or intestines and respond to hormonal cycling by expanding, bleeding, causing irritation and the formation of scar tissue. They can also collect to form a blood-filled cyst on the ovary called endometriomas.
But not all ovarian tumors are cancer. Dermoid cysts are the most common form of benign ovarian tumors in young women. These develop from germ cells which are primitive cells that are capable of producing eggs and all human tissues. A dermoid cyst is formed if the germ cells multiply bizarrely without fertilization, forming an encapsulated tumor that contains hair, sebaceous or oil materials, cartilage, bone, neural tissue and teeth. They range in size from 1 to 45 cm.
There are other types of cysts that arise from benign tumors and are more likely to occur in older women. They are called cystadenomas. These arise from cells on the outer surface of the ovary that secretes a watery or jelly-like fluid. Cystadenomas can become quite large and cause pain. The most worrisome are mucinous cystadenomas. They are filled with a sticky, thick, gelatinous material which can seed onto other pelvic and abdominal surfaces causing multiple growths and collections of mucinous fluid. These tend to recur and may ultimately be fatal.
Polycystic ovarian syndrome is a complicated endocrine condition in which the follicles develop, but do not normally erupt and extrude an egg. As a result, multiple small cysts remain under the ovary's surface causing the ovary to become mildly enlarged.
Most cysts do not cause symptoms and are discovered on routine pelvic exam. The incidence of ovarian cancer begins to increase after menopause. A blood test for the protein CA125 may be ordered to aid diagnosis. The final diagnosis is done through a laparoscopic procedure. Roughly 20% of women are diagnosed with an ovarian cyst or tumor at some point in their life, but only a small percentage of these women will be diagnosed with ovarian cancer.