The ovaries are part of the female reproductive system. They’re located in the lower abdomen on both sides of the uterus. Women have two ovaries that produce eggs as well as the hormones estrogen and progesterone.
Sometimes, a fluid-filled sac called a cyst will develop on one of the ovaries. Many women will develop at least one cyst during their lifetime. In most cases, cysts are painless and cause no symptoms.
There are various types of ovarian cysts, such as dermoid cysts and endometrioma cysts. However, functional cysts are the most common type. The two types of functional cysts include follicle and corpus luteum cysts.
During a woman’s menstrual cycle, an egg grows in a sac called a follicle. This sac is located inside the ovaries. In most cases, this follicle or sac breaks open and releases an egg. But if the follicle doesn’t break open, the fluid inside the follicle can form a cyst on the ovary.
Corpus luteum cysts
Follicle sacs typically dissolve after releasing an egg. But if the sac doesn’t dissolve and the opening of the follicle seals, additional fluid can develop inside the sac, and this accumulation of fluid causes a corpus luteum cyst.
Other types of ovarian cysts include:
Dermoid cysts: sac-like growths on the ovaries that can contain hair, fat, and other tissue
Cystadenomas: noncancerous growths that can develop on the outer surface of the ovaries
Endometriomas: tissues that normally grow inside the uterus can develop outside the uterus and attach to the ovaries, resulting in a cyst
Some women develop a condition called polycystic ovary syndrome. This condition means the ovaries contain a large number of small cysts. It can cause the ovaries to enlarge. If left untreated, polycystic ovaries can cause infertility.