Ovarian cysts are collections of fluids that are surrounded by a very thin wall within in the ovary. Ovarian follicles that are measured as larger than two centimeters are considered as ovarian cysts. These cysts vary in size, the smallest ones are about the size of a pea while the larger ones are about the size of an orange. These cysts affect women in every age, and they commonly occur during pregnancy. There are two types of ovarian cysts, the functional and non-functional.
Functional cysts are formed as part of a woman's regular menstural cycle. These cysts include:
- Corpus Luteum Cysts: These cysts appear after ovulation. Follicle sacs commonly dissolve after an egg is released, but if a sac doesn't dissolve and the follicle's opening seals, then a cyst is formed due to the accumulation of fluid within the sac.
- Follicular Cysts: These are considered to be the most common type of ovarian cyst. If a follicle containing the unfertilized egg will not rupture during the ovulation cycle, then a follicular cyst may be formed.
- Thecal Cysts: These cysts form within the thecal layer of cells encompassing the developing oocyte (the female gametocyte involved in reproduction). If there's an excessive hCG (human chorionic gonadotropin), then the thecal cells would quickly increase and thus become cystic.
Non-functional cysts, also known as benign ovarian cysts, are of a more serious nature. These cysts include:
- Ovarian Serous Cystadenoma: These cysts are very common benign ovarian tumours. They are unilocular cysts which have clear, straw-colored fluid.
- Dermoid Cysts: These are cysts which have developmentally mature skin with hair follicles and sweat glands, and with pockets of blood, fat, sebum, nails, teeth, cartilage, eyes, thyroid tissue and bone. Such cysts are always benign.
- Paraovarian Cysts: These fluid-filled cysts are epithelium-lined which are situated in the adnexa adjacent to the ovary and fallopian tube, and they constitute about ten percent of adnexal masses. Also called 'paratubal cysts'.
- Chocolate Cysts: These cysts are caused by endometriosis, and they are formed when a small patch of endometrial tissue bleeds, sheds a layer of dead skin, becomes transplanted, and grows in mass within the ovaries. Also known as 'endometrioid cysts' and 'endometrial cysts'.