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PCOS – Cysts vs Follicles, what’s actually occurring in PCOS?

PCOS – Poly Cystic Ovarian Syndrome. 

Polycystic Ovarian Syndrome (PCOS) is a condition not specific or limited to our ovaries. It impacts our overall health.  As it is follicles, not cysts occurring in PCOS. PCOS impacts much more than just our ovaries. Is it time for a much-needed name change?

What are the stats?

PCOS affects 12 -21 % of women of reproductive age. Up to 70% of women remain undiagnosed.

What are the diagnosis criteria?

PCOS is a condition that is a collection of symptoms that has no two women presenting with the same symptoms. Because diagnosis consists of a (Rotterdam) criteria, women don’t need all symptoms to be diagnosed.

The Rotterdam criteria require the presence of two of the following:

  • oligo/anovulation
  • hyperandrogenism
  • polycystic ovaries on ultrasound

With women presenting with a collection of symptoms, it is not surprising that up to 70% of women are undiagnosed.

What is going on with my ovaries?

PCOS suggests that the issue here is the ovaries, this couldn’t be more from the truth.

The ovaries arent the starting point. PCOS is a complex relationship between our metabolic and endocrine systems. This is what impacts our ovarian function. It is not the other way around. Women with PCOS have a higher risk of metabolic syndrome.

This is coupled with the fact, that these are not ovarian cysts, but follicles!

Now it starts to get even more confusing!


Hold the phone… yes, while the condition is named PCOS that’s incorrect.

What is the difference between a cyst and a follicle?

On ultrasound, simple cysts and follicles look the same. The difference is that a follicle has a microscopic oocyte (egg) maturing inside of it, a simple cyst does not.

What appear to be many small cysts are small antral follicles. These follicles are arrested part way through their development. The follicle’s growth and maturation have been inhibited.

These are known as atretic follicles. An ovarian follicle in an undeveloped state. These follicles can be viewed on the ovaries of almost all women who aren’t ovulating, regardless of the cause.

Cysts and follicles look the same on ultrasound. Doctors may need to use other factors to determine the difference. For example, follicles are usually small at the beginning of a menstrual cycle and grow as ovulation approaches. Additionally, the estrogen level increases as a follicle grow in size.

Ovary cyst, follicular.

A fluid-filled sac in the ovary is the most common type of ovarian cyst. It results from the growth of a follicle. A follicle is a fluid-filled cyst that contains an egg. In some cycles, this follicle grows larger than normal and does not rupture to release the egg. Normally it resolves with simple observation over days to months.

The difference is their size: 

  • a follicle is 10mm (2cm) or smaller
  • a dominant follicle is 20-30mm or smaller 
  • an ovarian cyst is larger than 30mm (3cm) in size 

I have cysts in my ovaries does that mean I have PCOS?

No, in young women, normal ovaries contain many small ‘cysts’ (fluid-filled sacs).

Follicles can be seen on ultrasound, or with the naked eye during surgery. These are not true ‘cysts’ because they are under 1cm in size and they are called follicles.

There can be up to 21 follicles in each ovary. This varies with age; young women generally have a lot of follicles, while women in their 40s have only a few and women past menopause usually have none.

PCOS is diagnosed when there are over 21 follicles. However, women with Hypothalamic amenorrhea can also have cysts.

Ovarian cysts are common. Nearly every woman will have one at some stage in her life. Many women will have no problems related to cysts.

So let’s recap.
  • It is follicles in the ovaries of women with PCOS not cysts.
  • PCOS is not limited to our ovaries or reproductive system.
  • PCOS is a multifaceted syndrome that impacts women differently.
  • It is normal to have ovarian follicles
  • PCOS impacts our endocrine and metabolic systems. 
  • It is normal to have ovarian cysts.
  • PCOS can not be diagnosed by ultrasound alone. 

What next?

If you have had a read of the above and you are still confused as to what is going on with your periods and your hormones.. I suggest making time to work together to understand what your hormones are doing. Some women can experience PCOS and HA, with often opposing treatment goals it is crucial to know what’s going on. You can understand your options to work with me.




Details of resources.

Volume 41, Issue 10, October 2012. Polycystic ovary syndrome An update

Jacqueline Boyle Helena J Teede

Medical Definition of Ovary cyst, follicular. Medical Editor: Melissa Conrad Stöppler, MD. Reviewed on 3/29/2021

Disordered follicle development
R Jeffrey Chang 1, Heidi Cook-Andersen
Affiliations expand
PMID: 22874072 PMCID: PMC3727408 DOI: 10.1016/j.mce.2012.07.011

Polycystic ovaries
K Lakhani 1, A M Seifalian, W U Atiomo, P Hardiman
Affiliations expand
PMID: 11806952 DOI: 10.1259/bjr.75.889.750009

Lindsay Carter Nautropath

Naturopathy is a holistic approach to wellness and health. Lindsay works to support women experiencing PCOS and acne.


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