What Is the Difference between PCOS & Polycystic Ovaries?

By BSc, MSc (embryologist) and BA, MA (fertility counselor).
Last Update: 12/18/2018

In today's society, Polycystic Ovaries (PCO) and Polycystic Ovary Syndrome (PCOS) are commonly confused terms, but one should note that they are not the same. In fact, PCO and PCOS have totally different causes and potential effects on female fertility.

By reading this article, you will learn the differences between them.

Does PCOS and PCO refer to the same?

Absolutely not. These disorders are completely different, though they have in common the fact that the woman has polycystic ovaries in both cases.

First and foremost, it is crucial that you learn about each condition briefly to learn more about the difference between PCO and PCOS.

What is PCO?

A polycystic ovary characterizes for the presence of 8 or more follicles in basal conditions, that is, in the phase of menstruation.

The size of these follicles normally ranges between 2 and 9 mm, and they are in a "resting" state, which means that they are not growing. This causes them to atrophy and turn into cysts, which is the main symptom of PCO.

What is PCOS?

On the other side of the coin, Polycystic Ovary Syndrome (PCOS) is a disease that alters the reproductive, endocrine, and/or hormone systems of the woman. PCOS alters the functioning of different hormones, affecting the fertility of the patient to a large extent.

Having polycystic ovaries is one of the most common symptoms of PCOS, hence the general confusion between them.

What are the main differences between them?

Even though they share a common symptom, there conditions differ in core aspects like:

  • Causes
  • Symptoms
  • Effect on fertility

What follows are the main differences between them in detail:


Having polycystic ovaries is considered a gynecologic characteristic of the female reproductive system. There is no explanation as regards why do they appear, but their origin is associated with the genetics of each woman. In other words, it is not considered a disorder in all cases.

In the case of PCOS, after several years of research, studies have shown that there is a genetic factor behind, since they have found a series of altered genes that could explain the origin of this pathology. Also, the woman's lifestyle has a great influence, especially when it comes to nutrition and health habits. Nonetheless, the main cause is still unclear.

To learn more about the possible causes of this disorder, visit this article: What Are the Causes of PCOS?


Broadly speaking, polycystic ovaries (PCO) have no symptoms. One of the few symptoms associated with PCO are irregular menstrual cycles, with a tendency to be longer than usual.

Normally, this situation does not cause hormone and/or reproductive irregularities that lead the woman to visit her OB/GYN. For this reason, it is usually diagnosed during routine visits.

As for PCOS, the possible and most worrying symptoms include:

Absent menstrual period or too sparse and/or sporadic periods.
Clinical and/or biochemical hyperandrogenism
Elevated levels of male hormones in blood, as well as hirsutism (hair that commonly appears in a male pattern in women) and excessive acne.
Excess body fat.
Polycystic ovaries
The ovaries contain multiple follicles in a resting state that causes them to have a necklace pattern.

Given that these symptoms is more obvious, it is not diagnosed by chance during routine visits. Indeed, problems caused by PCOS cause the woman to visit her doctor on purpose.

PCOS is considered a heterogeneous disorder, and symptoms vary from woman to woman, with different degrees of severity. This makes its diagnosis highly complicated.

To red about the criteria used to detect the presence of this female disorder, we recommend that you visit this article: How Is PCOS Diagnosed?

Infertility issues

Female infertility problems caused by PCO and PCOS are varied. The following are the different fertility issues each one of them can lead to.

Fertility with polycystic ovaries

As explained above, having polycystic ovaries does not automatically translated into having hormonal imbalances that could damage female fertility.

However, sometimes PCO does lead to menstrual irregularities that reduce the likelihood for the woman to get pregnant. The most common abnormalities derived from PCO are:

Due to the high number of follicles that grow in their ovaries, these women can have menstrual cycles without ovulation.
This menstrual irregularity causes the woman to have cycles longer than 35 days. In these cases, determining the day of ovulation (if it occurs) is hard. As a consequence, determining the optimal days for trying to conceive is highly difficult.

Fortunately, these complications are easily solvable with ovulation induction medications, which allow cycles to be regulated again, and to achieve pregnancy naturally. Thanks to ovulation induction drugs, hormone production is increased and subsequently follicle growth in the ovaries. Normally, these drugs are administered by mouth route for 4-5 days, and they are rather cost-affordable.

In some cases, monitoring the treatment via ultrasound scan is necessary in order to being able to determine the ovulation days and to schedule sex relations.

Fertility with PCOS

In the case of Polycystic Ovary Syndrome (PCOS), there is a direct relationship with infertility due to hormone alterations caused by it.

Too elevated androgen levels in blood prevent proper follicle development. When egg-containing follicles cannot complete their maturation process, they are unable to release an egg. As a consequence, they become atretic. This situation can get even worse due to irregular levels of LH and insulin. Too high levels of these hormones affect ovulation and egg quality, too.

Normally, women with PCOS require a stimulation cycle with gonadotropins, which are administered with injections. This cycle is necessary given the lack of a sufficient number of natural ovulation inductors. During this phase, a greater number of ultrasound scans and bloodworks is necessary to monitor how it progresses.

With PCOS, the fertility treatments are more complex due to the severity of the alterations it causes.

Based on the level of severity PCOS comes with, as well as on the quality of the semen sample used, the technique of choice can be as simple as timed intercourse, or more technically challenging, such as IUI or IVF with ICSI.

If you need to undergo IVF to become a mother, we recommend that you generate your Fertility Report now. In 3 simple steps, it will show you a list of clinics that fit your preferences and meet our strict quality criteria. Moreover, you will receive a report via email with useful tips to visit a fertility clinic for the first time.

FAQs from users

My ovaries have a polycystic appearance, can it turn into PCOS?

By Victoria Moliner BSc, MSc (embryologist).

Having polycystic ovaries does not mean that you will end up developing Polycystic Ovary Syndrome (PCOS) in the future. Nonetheless, if you develop other types of hormone irregularities, you are more likely to develop PCOS.

Simply put, the fact that your ovaries have multiple follicles does not mean you are going to have PCOS by default.

My ovaries are plenty of cysts, does it mean I am less fertile?

By Victoria Moliner BSc, MSc (embryologist).

To determine if the presence of multiple cysts is affecting your fertility, you need to visit a doctor to run a series of tests: a blood test to check your hormone levels, as well as a physical exploration to look for potential signs of hyperandrogenism.

Suggested for you

The treatment options available to solve the symptoms associated with these situations are very different. With PCOS, women are prescribed medications to try to regulate hormonal levels, while this action is unnecessary with PCO. Want to learn more about the treatment for PCOS? Click here: Treatment of Polycystic Ovary Syndrome.

As explained above, in case you have PCOS and want to have a baby, the fertility treatment recommended for you depends on the severity level of your case. In most of the cases, ovarian stimulation is needed. To get more info about it, see also: Ovarian Stimulation Protocols for IVF – Process & Medications Used.

To dismiss the possibility that a woman with multiple ovarian cysts has PCOS, she should visit her OB/GYN to undergo a series of diagnostic tests. Learn more about the tests required to assess your fertility here: Female Fertility Tests – How Do You Know if You Can’t Get Pregnant?

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FAQs from users: 'My ovaries have a polycystic appearance, can it turn into PCOS?' and 'My ovaries are plenty of cysts, does it mean I am less fertile?'.

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 Victoria Moliner
Victoria Moliner
BSc, MSc
Degree in Biochemistry and Biomedical Sciences from the University of Valencia (UV). Master's Degree in Biotechnology of Human Assisted Reproduction from the UV and the Valencian Infertility Institute (IVI). Presently, she works as a Research Biologist. More information about Victoria Moliner
Adapted into english by:
 Sandra Fernández
Sandra Fernández
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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