Ovarian Cysts in Women with PCOS

Ovarian cysts are the name giver of PCOS, which stands for Polycystic Ovarian Syndrome. The word “poly” is derived from a Greek word meaning “many”, and “cystic” is referring to fluid filled follicles. Therefore, if you have ovarian cysts, it means that you have small, fluid-filled sacs  or pockets in and around your ovaries that appear like a string of pearls on an ultrasound scan.

Having cysts is part of the Rotterdam Criteria, which are used to diagnose PCOS. For a diagnosis you need to have two out of the three following criteria:

  • Irregular or absent cycles due to a lack of ovulation
  • Ovarian cysts
  • High androgen levels

This means, that even though ovarian cysts are very common among women with PCOS and part of the Rotterdam Criteria, having cysts on the ovaries is not mandatory for a PCOS diagnosis. At the same time, you can have cysts on your ovaries (PCO – Polycystic Ovaries) and not have PCOS.

Let’s further explore some different types of ovarian cysts and their potential risks, as well as have a closer look at the cysts that are present in women with PCOS

 Normal Ovary vs. Ovarian Cysts PCOS 

Different Types of Ovarian Cysts

Follicle and Corpus Luteum Cysts

Follicle cysts are the most common types of cysts and develop as part of the menstrual cycle. During each cycle, an egg grows inside a sac called a follicle. The follicle matures and normally releases the egg. If this happens, ovulation takes place. In case the follicle didn’t break open and release the egg, it can remain inside the ovary for one to three more months until it dissolves on its own. A maturing follicle usually reaches a size of about 2 cm in diameter.

After ovulation has taken place and the follicle has released the egg, the corpus luteum forms out of the remains of the follicle. If the opening of the follicle seals, additional fluid can develop inside the sac and cause a corpus luteum cyst. These cysts usually dissolve after a few weeks, but some can grow in size to up to 10 cm wide. They may also bleed or twist the ovaries and cause severe pain. Some medications like chlomid, which is used to induce ovulation, may raise the risk of getting corpus luteum cysts.

Dermoid cysts

These kinds of cysts are present at birth (congenital) and can occur in various places of the body, one of them being the ovaries. They’ve got nothing to do with the menstrual cycle. Dermoid cysts can contain structures such as hair follicles, teeth, and glands that produce sweat or skin oil, which cause these cysts to grow slowly. They can be present long time before they are discovered during an ultrasound scan.


Women with endometriosis may develop cysts called endometrioma. Endometriosis is an inflammatory condition where uterine tissue grows outside the uterus. This tissue also builds up and breaks down just like the uterine lining. The endometriosis tissue may attach to the ovary and form a growth. Endometrioma can be painful during intercourse or when menstruating. These cysts are often called chocolate cysts because of the dark color of the fluid within them.


These cysts are noncancerous growths that can develop on the outer surface of the ovaries.They are attached to the outside of the ovary and can grow quite large. Cystadenomas are rarely cancerous and need to be removed surgically.

Ovarian Cysts in Women with PCOS

Ovarian cysts in women with PCOS are similar to follicle cysts, but they aren’t classified as such. The main feature of cysts in women with PCOS is their quantity. For a PCOS diagnosis there need to be a minimum of 12 cysts with a size of 2 to 9 mm in diameter present in or around a single ovary. With newer technology, the total number in both ovaries may be 26. An ovary can also be classified as polycystic with an ovarian volume bigger than 10 cm in diameter. The size of a healthy ovary is usually just that of an almond.

Follicle Development Ovary Follicle Development Ovary

How Do Ovarian Cysts in Women with PCOS Develop?

In the beginning of a healthy menstrual cycle, about a handful of follicles, each containing an egg, are being recruited from the ovarian reserve. Those follicles will grow and mature, produce estrogen and, around day 7 or 8 of your cycle, the best follicle will be chosen to become the primary follicle. It will further grow and mature until it releases the egg on the day of ovulation.

In women with PCOS, due to elevated levels of testosterone, this process runs slightly differently. More than just a handful of follicles are being chosen as primary follicles at the beginning of a menstrual cycle, but none of them will reach the maturation stage – meaning, no dominant follicle will be chosen and release its egg for fertilization. On top of that, no signal is given for the remaining follicles to involute, so they remain in the ovary appearing like a string of pearls in an ultrasound scan. These follicles are usually harmless, but they can produce more testosterone and sometimes even grow in size.

As you can see, cysts seen in women with PCOS are quite a spectacular phenomenon. While you are trying to manage your symptoms, try to wear your pearls with pride.

Sending you my love,

Nadine 🧡

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