There are several different kinds of ovarian cyst, which are categorised as either:
- functional cysts (the most common type): harmless cysts that form as part of the menstrual cycle, or
- pathological cysts: tumours in the ovaries that are either benign (harmless) or malignant (cancerous).
There are two types of functional ovarian cyst:
- follicular cyst, and
- luteal cyst.
Follicular cysts are the most commonly seen ovarian cysts.
The ovaries are two small, round organs in the female reproductive system that release an egg every month. The egg moves into the womb, where it is fertilised by a man's sperm.
Each egg is formed in a tiny structure inside the ovary called a follicle. The follicle contains fluid to protect the egg as it grows, and bursts when the egg is released.
Sometimes, a follicle does not release an egg, or does not shed its fluid and shrink after the egg is released. If this happens, the follicle can get bigger as it swells with fluid. This becomes a follicular ovarian cyst.
Usually, only one cyst appears at a time. It normally goes away without treatment after a few weeks.
Luteal cysts are less common. They develop when the tissue that is left behind after an egg has been released (the corpus luteum) fills with blood.
Luteal cysts usually go away on their own within a few months, but can sometimes rupture (split), causing internal bleeding and sudden pain.
In women under the age of 30, dermoid cysts are the most common type of pathological cyst.
Past the age of 40, tumours called cystadenomas are the most common type of pathological cyst.
Dermoid cysts (also known as mature cystic teratomas) can contain a range of tissues, such as hair, skin or teeth, because they form from cells that make eggs. Dermoid cysts may need to be surgically removed.
Cystadenomas develop from cells that cover the outer part of the ovary. There are different types. Some are filled with a watery liquid and others with a thicker, mucous substance.
Cystadenomas are often attached to an ovary by a stalk rather than growing inside the ovary itself, which means they can grow to a large size. They are not normally cancerous, but need to be surgically removed.
Pain: Pain is an unpleasant physical or emotional feeling that your body produces as a warning sign that it has been damaged.
Benign: Benign refers to a condition that should not become life-threatening. In relation to tumours, benign means not cancerous.
Cysts: A cyst is a fluid-filled sac or cavity in the body.
Blood: Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.
Uterus: The uterus (also known as the womb) is a hollow, pear-shaped organ in a woman where a baby grows during pregnancy.
Tissue: Body tissue is made up of groups of cells that perform a specific job, such as protecting the body against infection, producing movement or storing fat.
Rupture: A rupture is a break or tear in an organ or tissue.
Ovaries: Ovaries are the pair of reproductive organs that produce eggs and sex hormones in females.