During ovulation (the process during which the egg ripens and is released from the ovary) the ovary produces a hormone to make the follicles (sacs containing immature eggs and fluid) grow and the eggs within it mature.
Once the egg is ready, the follicle ruptures and the egg is released. Once the egg is released, the follicle changes into a smaller sac called the corpus luteum. Ovarian cysts occur as a result of the follicle not rupturing, the follicle not changing into its smaller size, or doing the rupturing itself.
There are five (5) common types of ovarian cysts: functional cysts, polycystic ovaries, endometrial cysts, cystadenomas and dermoid cysts.
There are two types of functional cysts - follicle cyst and corpus luteum cyst. Both of these types of cysts develop as part of the natural function of the ovary.
- Follicle Cyst. This cyst occurs during ovulation when an egg is released into the fallopian tube or when a developing follicle fails to rupture. These cysts grow from 1½ inches to 2 inches in diameter, and will usually dissolve within one to three months.
- Corpus Luteum Cyst. This cyst is caused by a malfunction of the corpus luteum. Unless a woman is pregnant, the corpus luteum disintegrates. But in the formation of a corpus luteum cyst, it fills with fluid and remains in the ovary.
Polycystic ovaries (also known as polycystic ovarian syndrome or disease) is a condition in which the follicles never erupt from the ovaries.
Under normal circumstances, follicles grow, mature, and rise to the surface of the ovary, where they burst and release an egg to the Fallopian tube, a process controlled by pituitary hormones. The remnants of the burst follicle then begin to produce progesterone, which stimulates the lining of the uterus (endometrium) to grow thicker in case it needs to support a fertilized egg. The effect on the pituitary of an increase in progesterone production is to signal it to stop stimulating the development of eggs.
In polycystic ovaries, the follicles grow just under the ovaries' surface, and are produced again and again because the pituitary has not been signaled to shut off. Both ovaries become filled with tiny cysts and can become enlarged.
Endometrial cysts (also known as endometriomas or "chocolate cysts" (filled with dark blood)) form as a result of endometriosis. endometriosis is a disease in which the endometrial tissue normally found in the uterus grows in other areas. After successive menstrual cycles, this misplaced endometrial tissue bleed, gradually forming endometrial cysts. Over time the cysts grow and can become as large as a grapefruit.
Cystadenomas are known as neoplasms (new growths). Ovarian neoplasms are new and abnormal formations that develop from the ovarian tissue. There are two (2) types of cystadenomas - serous and mucinous.
Serous cystadenoma is filled with a thin watery fluid and can grow to be between 2 inches to 6 inches in diameter.
Mucinous cystadenoma is filled with a sticky, thick gelatinous material and can grow to be between 6 inches to 12 inches in diameter. There have been rare cases where the cyst measured 40 inches in diameter and weighed over 100 pounds.
Dermoid cysts are also known as ovarian neoplasms and consist of skin or related tissue such as hair, teeth or bone instead of fluid like the cystadenomas. Dermoid cysts develop from the ovary's germ cells (cells that produce the egg and the beginnings of all human tissues). Dermoid cysts may be present at birth but are not noticed until adulthood. They generally measure between 2 inches to 4 inches in diameter.