Ovarian cysts are fluid-filled sacs in an ovary. There are several types of cysts. The most common are ones that develop in the follicles (cavities where eggs develop) or corpus luteum (the empty follicle remaining after an egg is released).
Other types include dermoid cysts and cystadenomas, which can grow very large.
Multiple ovarian cysts, together with other characteristic features, occur in polycystic ovarian syndrome. Most cysts cause no symptoms.
When symptoms do occur, they may include abdominal discomfort, pain during sex, and menstrual irregularities. Occasionally, a cyst may rupture or become twisted, causing symptoms such as severe abdominal pain, nausea, and fever.
Rarely, a cyst may become cancerous.
In most cases, cysts disappear naturally without treatment.
A large cyst, one that has ruptured or twisted, or one that may become cancerous is treated by surgical removal.