What Is The Difference Between Ovarian Cysts And PCOS?

Pictures of ovarian cysts
What Is The Difference Between Polycystic Ovary Syndrome And Ovarian Cysts?

Polycystic ovary syndrome is a 'syndrome' - that is, a condition where a collection of symptoms occur together. One of those symptoms is multiple ovarian cysts. However it is quite possible for a woman to have multiple ovarian cysts without having PCOS. In order for a PCOS diagnosis to be made, she will also need to show other signs of PCOS such as excessive facial hair, absent or irregular periods and fertility issues.

Main Types Of Ovarian Cysts

An ovarian cyst is a fluid filled sac (like a blister) that occurs in or on the ovaries. They are different types ovarian cysts and they are differentiated primarily by (a) what type of substance they are filled with and (2) how many there are.

Corpus Luteum picture scan
Functional cyst seen in one ovary, using imaging technology

Functional Cysts
By far the most common type of ovary cyst. Functional cysts are closely linked to the menstrual cycle. All women naturally have cysts on their ovaries - during a menstrual cycle eggs develop in these cavities and during ovulation they rupture and the egg is released. But sometimes there are problems with the process. For example, they may not rupture and so continue to swell, or other times they do rupture but instead of dissolving, the sacs seal off and fluid builds up inside. This is known as a functional cyst. Most functional cysts disappear naturally after a few cycles and are quite harmless.

picture of multiple cysts on mri scan
PCOS, cysts occuring in both ovaries. Note the typical string of pearl appearance.

Polycystic Ovary

'Poly' means many. If there are many cysts on the ovaries, you are said to have a polycystic ovary. However, in order for polycystic ovary syndrome to be diagnosed, you need to display more characteristics, like excessive body hair or fertility problems, as mentioned above. If a woman has PCOS typically an ultrasound scan will show 10 or more cysts, usually less than 5mm each, and they will have a characteristic string of pearls appearance. The ovaries will also look swollen (although 30 percent of patients have normal sized ovaries).

Endometriosis is a condition where cells from the uterus (endometrial cells) instead of being flushed out through the vagina during a normal menstrual cycle, stick to other organs in the body. They build up every month into blood filled cysts and break down and bleed as they would were they still in the womb. They can attach to the outside of the womb, the fallopian tubes, pelvic cavity and the ovaries. When they attach to the ovaries they are referred to as endometriomas. This is a common cause of infertility. See also can ovarian cysts cause infertility?

Dermoid Cysts
Dermoid cysts are not filled with fluid, but are solid and contain clumps of hair, bone and even teeth. They are not thought to result from a pregnancy but from the woman's own cells, which are stimulated to grow in this way for unknown reasons. Normally benign (non cancer forming) they can become large causing pain. See, what type of pain do ovarian cysts cause?

Related Questions
Personal stories and symptoms: What are the signs of ovarian cysts?
Diagrams of the female body and the human body.
Pregnant or just cysts? Can ovarian cysts cause a missed period?
Treatment options: Do ovarian cysts usually need to be surgically removed?
Know your body: Development of the female body.

• Need more information? See: Guide to Ovarian Cysts
• Got another question? See: Womens Health Questions

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