PCOS vs. ovarian cysts: what's the difference?

Eduardo Hariton, MD, MBA - Contributor Avatar

Written by Rissy La Touche 

Eduardo Hariton, MD, MBA - Contributor Avatar

Written by Rissy La Touche 

last updated: May 04, 2021

5 min read

Polycystic ovary syndrome (PCOS) and ovarian cysts: They both have "cyst" in their names, but are the two conditions one and the same? The short answer is no. You'll get the long answer by the time you finish this article, but we'll give you a quick explainer up front:

  • PCOS is a hormonal disorder that's sometimes accompanied by polycystic ovaries — these don't have cysts, but instead have a higher-than-average number of small (2-8 mm) antral ovarian follicles (fluid-filled sacs that house and release eggs).

  • Any follicle, including those present in polycystic ovaries, can become a follicular cyst (the most common type of ovarian cyst) — which grows during the menstrual cycle and is filled with clear fluid.

  • Other types of ovarian cysts — teratomas, cystadenomas, and endometriomas — are considered "true" cysts because they contain biological material instead of just fluid, and they aren't directly related to the menstrual cycle.

Keep reading to better understand what PCOS is, the kinds of ovarian cysts that can occur, and what ultimately sets the two types of ovarian issues apart.

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What is polycystic ovary syndrome (PCOS)?

Polycystic ovary syndrome (PCOS) is a hormonal disorder that impacts as many as 1 in 10 people with ovaries. Even as prevalent as PCOS is, it can often go undiagnosed and undertreated (one study put this at 70%!).

The “syndrome” in PCOS denotes a group of symptoms that consistently occur together as part of the condition. As such, a diagnosis of PCOS results when two of the three following symptoms are confirmed (this is also known as the Rotterdam criteria): irregular periods or ovulationelevated levels of androgens or excess hair growth, and/or "polycystic" ovaries.

  1. Irregular menstruation or ovulation, or lack thereof, is defined as no menstruation for at least three months, or 35+ day menstrual cycles. Irregular ovulation may result in more buildup of the lining of the uterine walls (endometrium) in between menstrual periods, often causing heavier periods with higher levels of pain and discomfort.

  2. Elevated levels of androgens, which are a group of hormones critical to reproductive development — the most well-known being testosterone. While androgens are sometimes called "male" hormones, they're produced in people with ovaries too — and testosterone in particular has an impact on everything from body composition to insulin sensitivity.

  3. "Polycystic" ovaries are enlarged and contain multiple immature ovarian follicles (12 or more on one side).

What are the symptoms of PCOS?

Some of the most common symptoms of PCOS include:

  • Excessive body hair growth (aka hirsutism)

  • Acne

  • Weight gain

  • Trouble getting pregnant (due to irregular ovulation)

How is PCOS diagnosed and treated?

Any one of the Rotterdam criteria could have other causes individually, so PCOS diagnosis by a medical provider is important for getting a full picture of your health and may include taking your medical history, fertility hormone testing, a pelvic exam, and even measuring sugar metabolism to evaluate for insulin resistance.

Since only two out of the three Rotterdam criteria are needed to diagnose PCOS, ultrasounds to confirm the presence of polycystic ovaries aren't always required if the other two criteria are met. And in some cases, symptoms may be enough to identify high androgen levels without hormone testing.

Treatment for PCOS can include:

What are ovarian cysts?

Ovarian cysts (sometimes called adnexal masses) are quite common in people with ovaries, with prevalence suggested at anywhere from 8% to 18%. Ovarian cysts are usually harmless, coming and going with no symptoms at all. There are many types of ovarian cysts, but here are four common ones:

  • Functional cysts are the most common type of ovarian cyst and occur in the majority of people with ovaries. They usually disappear on their own and cause no symptoms. There are two types of functional cystsCorpus luteum cysts occur anytime an ovarian follicle releases its egg, while follicular cysts occur when a follicle fails to release its egg and continues to grow.

  • Teratomas (or dermoid cysts) are cysts that contain a variety of tissues that make up the body like skin, hair, and sometimes teeth. In rare cases, teratomas can be cancerous (called immature teratomas).

  • Cystadenomas form on the outer surface of the ovary. While they can grow quite large, they are typically benign.

  • Endometriomas form as a result of endometriosis, a condition where tissue similar to the lining of the uterus grows outside of the uterus.

The above list is not exhaustive: There are many other rare types of benign or malignant cysts that can present in the ovary. While covering all types is beyond the scope of this article, it's important to know they exist.

Symptoms of ovarian cysts (some of which can overlap with PCOS) include:

Dr. Eduardo Hariton, MD, MBA, an OB-GYN and reproductive endocrinology and infertility fellow at the University of California in San Francisco, explains that the symptoms of all different types of ovarian cysts usually overlap. That's why, he says, it's "hard to tell the type of cyst from symptoms alone."

How are ovarian cysts diagnosed and treated?

A medical provider can confirm the presence of a cyst via a pelvic exam. Determining the type of cyst is done via blood tests, pregnancy test, a pelvic ultrasound, and/or laparoscopy — where a small camera is used to visualize the inside of the abdomen and see the ovaries and any possible cysts. Treatment is based on the size of the cyst, whether it's fluid filled, solid, or mixed, the appearance of the cyst, and whether or not the patient has been through menopause.

Treatment of ovarian cysts can include:

  • A "watch and wait” approach that incorporates pain management

  • Surgical intervention in rare cases when the cyst is overly large, causes internal bleeding due to rupture, or is expected to be cancerous

Often, ovarian cysts resolve by themselves within a few menstrual cycles — and around 8% of premenopausal people have ovarian cysts that require treatment.

Can either PCOS or ovarian cysts impact fertility?

PCOS is one of the leading causes of infertility. Since PCOS can result in irregular ovulation, it can often be difficult to detect a person’s fertile window (the days when they're most likely to conceive) in order to achieve pregnancy. In those situations, ovulation predictor kits can help predict ovulation — even if it's irregular. Some people with PCOS don't ovulate at all, which makes it impossible to get pregnant.

Most ovarian cysts don't affect fertility, aside from endometriomas (which are caused by endometriosis). Endometriosis on its own can block off the fallopian tubes, which is where an egg travels to meet up with sperm, or otherwise diminish fertility.

Putting it all together: What are the biggest differences between "polycystic" ovaries and ovarian cysts?

In the context of polycystic ovaries, "cyst" is a bit of a misnomer. As it's explained in one 2014 study, a cyst is "an epithelial-lined (thin tissue on the surface of organs), fluid-filled sac usually greater than 2 cm." In PCOS, "ovaries are usually enlarged and contain multiple [small] follicles, typically less than 8 mm, that are not lined by epithelium." Put simply, polycystic ovaries can be an outcome of regular ovulation not occurring — leading to multiple small follicles on the ovaries. Patients without PCOS have the same type of follicles, but on average, fewer of them.

Dr. Hariton says his patients have trouble understanding the differences between polycystic ovaries and ovarian cysts "all the time." "It's a big problem with the misnomer," he explains. So… what are those differences exactly? The multiple small ovarian follicles in polycystic ovaries sometimes, but not always, result in follicular cysts — but follicular cysts can also happen in people without PCOS. Follicular and corpus luteum cysts both change in response to different phases of the menstrual cycle. On the other hand, teratomas, cystadenomas, and endometriomas aren't directly related to the menstrual cycle.

The bottom line

While PCOS and ovarian cysts may have some overlap, they are distinct in terms of their outcomes and treatment approaches. And while this guide should set you off on the right foot in understanding how PCOS and ovarian cysts compare and contrast, it's always important to talk to your healthcare provider if you're experiencing any issues so they can help you get to the bottom of them.

This article was reviewed by Dr. Eduardo Hariton, an OB-GYN and reproductive endocrinology and infertility fellow at the University of California in San Francisco.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

May 04, 2021

Written by

Rissy La Touche

Fact checked by

Eduardo Hariton, MD, MBA

About the medical reviewer