• Also Known As:
  • PCOS
  • Stein-Leventhal Syndrome
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What is polycystic ovary syndrome?

Polycystic ovary syndrome (PCOS) is a hormone disorder that affects teenage girls and women. It is the most common endocrine disorder in women.

Polycystic means “many cysts.” A main feature of PCOS is that eggs are not released from the ovaries. Instead, fluid builds up around the eggs, forming sacs (cysts). Though this feature is the origin of the name of the disorder, not all women diagnosed with PCOS have polycystic ovaries.

The underlying causes of PCOS are not well understood, but it is believed that an imbalance of sex hormones and resistance to the effects of the hormone insulin (insulin resistance) are the main problems. These problems can result in a defined group of signs, symptoms and complications, such as excess facial and body hair, weight gain, irregular menstrual periods, infertility, and increased risk of diabetes and heart disease.

  • About 5 to 6 million American women have PCOS, but many don’t know they have it.
  • It is the leading cause of infertility in the U.S., which affects as many as10% of women of childbearing age.
  • The condition can occur at any age after puberty.
  • While the exact underlying causes of PCOS are not known, there is a genetic component. Women with mothers or sisters who have PCOS are twice as likely to have the condition.

PCOS can be hard to recognize and diagnose. Some women and girls may only have a few features of the condition and these may change over time, both in terms of severity and which features are expressed. Some features, such as weight gain and excess facial and body hair, can vary between ethnic groups.

Healthcare practitioners will typically diagnose a woman (adult female) as having PCOS if she has at least two of the following features:

  • Excess male hormones (androgens)—evidence of this may include a high blood testosterone level, for example, or symptoms such as acne (sometimes severe) and excess hair growth, which can be on the face, stomach and/or back.
  • Problems with ovulation—this may include having no menstrual periods, irregular menstrual cycles, or infertility.
  • Ultrasound results that show large ovaries with many small follicles that look like cysts (No ultrasound may be needed if a woman has both of the first two features.)

In teen girls, however, the above criteria are not used to help make a diagnosis because teen girls normally have irregular menstrual periods or missed periods the first two years after starting to menstruate. Additionally, ultrasound may not be helpful in detecting cysts on their ovaries. Rather, healthcare practitioners may use hormone blood tests and signs and symptoms of excess male hormones to help diagnose PCOS in teen girls.

Hormone Imbalance in PCOS

Though they are called “male hormones,” androgens are normally produced in small amounts in females by the ovaries and adrenal glands. However, when there is an excess of male hormones, such as testosterone, you can experience signs and symptoms such as excess facial and body hair (hirsutism) and acne.

These hormonal imbalances can also disrupt the monthly menstrual cycle, causing irregular periods that occur more or less frequent than monthly. This can prevent the release of eggs (ovulation) during the cycle and may lead to infertility.

When you do not menstruate or ovulate, not enough of the hormone progesterone is produced. This hormonal imbalance can lead to an overgrowth of the lining of the uterus (endometrial hyperplasia) and increase the risk of endometrial cancer. If you do ovulate and become pregnant, you may have an increased risk of complications such as miscarriage.

In PCOS, eggs that do not mature fully are not released during ovulation and the immature eggs remain in the ovary as pearl-sized, fluid-filled sacs. Over the course of time, many cysts may develop into what looks like a string of beads when viewed by ultrasound imaging. In as many as 90% of women (adult females, not teen girls) with PCOS, an ultrasound of the ovaries will reveal cysts. Both ovaries tend to be enlarged, as much as three times their normal size.

Insulin Resistance in PCOS

It is thought that insulin resistance may be a key factor in PCOS. Insulin resistance is a decreased ability of the body to respond to the effect of insulin, a hormone that helps transport glucose into the body’s cells, where it is needed for energy production. When there is resistance to insulin’s effect, the body tries to compensate by making even more insulin and releasing it in the blood (hyperinsulinemia). It is thought that too much insulin may cause the ovaries to increase androgen production, which in turn causes the symptoms associated with PCOS.

Most women with PCOS have some degree of insulin resistance, weight gain, and abnormal blood lipid levels. However, insulin resistance tends to be even more pronounced in women who are obese and do not ovulate. These conditions increase the risk of type 2 diabetes, high blood pressure (hypertension), cardiovascular disease, and metabolic syndrome (a condition that can lead to diabetes and heart disease).


About PCOS

Signs and Symptoms

Signs and symptoms of PCOS can vary widely. Some girls and women may have only a few signs and symptoms while others may experience several of them. Even within the same woman, the number of symptoms experienced and their severity can change over time.

Some examples of PCOS signs and symptoms include:

  • Irregular menstrual periods, no menstrual periods, or abnormal uterine bleeding
  • Ovaries with multiple cysts, enlarged ovaries
  • Pelvic pain
  • Excess facial and body hair growth (hirsutism)
  • Weight gain or obesity, especially with fat distribution in center of the body. However, there are some women who can have excess androgens and other features of PCOS despite having a relatively normal weight.
  • Acne, darkening or thickening of the skin (acanthosis nigricans) and/or skin tags in the armpits or neck
  • Thinning hair, loss of hair from the top of the head
  • Deeper voice (rare)


Some of the complications associated with PCOS include:


At present, there is no single test that can diagnose PCOS. A healthcare practitioner will typically evaluate a combination of clinical findings such as signs and symptoms, medical and family history, and physical exam, as well as laboratory test results to help make a diagnosis.

Some testing may be done to rule out other possible causes of symptoms before a PCOS diagnosis can be made. For example, tumors of the adrenal gland or ovary, or an enlarged adrenal gland (adrenal hyperplasia) can also cause excess androgens in women.

Laboratory Tests

A few blood tests for hormones may be used to aid in the diagnosis of PCOS:

Some secondary tests may be done, such as:

A few tests may help rule out other conditions with similar signs and symptoms:

If you are diagnosed with PCOS, some blood tests may be done to check and monitor your general health and detect any complications that might develop:

Non-Laboratory Tests

As mentioned above, a pelvic ultrasound (transvaginal and/or pelvic/abdominal) may be used to evaluate the ovaries, to look for cysts and to see if the ovaries are enlarged and whether internal structures appear normal.

  • In PCOS, the ovaries may be 1.5 to 3 times larger than normal and characteristically have more than 20 follicles per ovary.
  • If present, the cysts are often lined up on the surface the ovaries, forming the appearance of a “pearl necklace.”

The ultrasound helps visualize these changes in more than 90% of women with PCOS, but they are also found in up to 25% of women without PCOS symptoms. (For more, see RadiologyInfo.org: Pelvic ultrasound.)

Laparoscopy may be used to evaluate ovaries and sometimes used as part of surgical treatment. (For more, see MedlinePlus: Pelvic laparoscopy.)


  • There is no cure for polycystic ovary syndrome (PCOS) and it does not go away on its own. Treatment of PCOS is primarily aimed at relieving symptoms and preventing complications. Your options depend on the type and severity of your symptoms and your desire to become pregnant. Talk to your healthcare practitioner about what options are best for you.

    • Diet, exercise, and maintaining a healthy body weight are important strategies for treating PCOS and may help many women manage symptoms. These lifestyle changes are recommended to help decrease insulin resistance. Regular exercise and healthy foods will help lower blood pressure and cholesterol as well as improve sleep apnea problems. Refraining from smoking cigarettes or other tobacco products also may lower androgen levels.
    • Drugs such as metformin may be prescribed to treat insulin resistance and diabetes. Metformin may also help to regulate menstrual periods and encourage ovulation.
    • Antibiotics or retinoic acids may be used to treat acne.
    • Oral contraceptives may be prescribed to help normalize menstrual periods.
    • Other medications may also be prescribed to:
      • Stabilize hormone levels
      • Treat more severe acne and/or excess hair
      • Encourage or induce ovulation
      • Decrease the risk of endometrial cancer

    Waxing, shaving, depilatory, and electrolysis or laser treatments may be used to remove excess facial and body hair.

    For more on treatment, see the resources in the Related Content section.

View Sources

Sources Used in Current Review

(August 2018) International evidence-based guideline for the assessment and management of polycystic ovary syndrome 2018. Available online at https://www.monash.edu/__data/assets/pdf_file/0004/1412644/PCOS-Evidence-Based-Guideline.pdf. Accessed October 8, 2019.

(June 2017) American College of Obstetricians and Gynecologists. Polycystic ovarian syndrome FAQ. Available online at https://www.acog.org/Patients/FAQs/Polycystic-Ovary-Syndrome-PCOS. Accessed November 2019.

(August 2, 2019) Kovacs P. Polycystic ovary syndrome: 5 things you might not know. Available online at https://www.medscape.com/viewarticle/916211. Accessed November 2019.

(August 29, 2017) Mayo Clinic Staff. Polycystic ovarian syndrome (PCOS). Available online at https://www.mayoclinic.org/diseases-conditions/pcos/symptoms-causes/syc-20353439. Accessed November 2019.

(January 31, 2017) National Institutes of Health. About polycystic ovarian syndrome (PCOS). Available online at https://www.nichd.nih.gov/health/topics/pcos/conditioninfo. Accessed November 2019.

(July 2018) The Endocrine Society. Polycystic ovarian syndrome (PCOS) for teens. Available online at https://www.hormone.org/diseases-and-conditions/polycystic-ovary-syndrome-pcos-for-teens. Accessed November 2019.

(September 2018). The Endocrine Society. Polycystic ovarian syndrome. Available online at https://www.hormone.org/diseases-and-conditions/polycystic-ovary-syndrome. Accessed November 2019.

(February 28, 2018) Lucidl RS. Polycystic ovarian syndrome. Available online at https://emedicine.medscape.com/article/256806-overview. Accessed November 2019.

(March 29, 2019) Dunaif, A. Keep It Simple: What Endos Really Need to Know About PCOS. Medscape Commentary. Available online at https://www.medscape.com/viewarticle/910940. Accessed January 2020.

(July 2018) Teen Health from Nemours. Polycystic Ovary Syndrome (PCOS). Available online at https://kidshealth.org/en/teens/pcos.html. Accessed February 2020.

(July 2018) Hormone Health Network. Polycystic Ovary Syndrome (PCOS) for Teens. Available online at https://www.hormone.org/diseases-and-conditions/polycystic-ovary-syndrome-pcos-for-teens. Accessed February 2020.

(April 1, 2019) Office on Women’s Health. Polycystic ovary syndrome. Available online at https://www.womenshealth.gov/a-z-topics/polycystic-ovary-syndrome. Accessed February 2020.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

Bradley, C. (2002 February 4). Ovarian overproduction of androgens. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001165.htm.

Sadovsky, R. (2001 December 15). Androgen Deficiency in Women: Review of the Subject. American Family Physician, Tips from Other Journals [On-line Journal, info from Miller, KA. Androgen deficiency in women. J. Clin Endrocrinol Metab 2001;86:2395-401]. Available online at http://www.aafp.org/afp/20011215/tips/6.html.

Alberta Clinical Practice Guidelines Steering Committee (2001 June, Revised). Laboratory Endocrine Testing Guidelines. Alberta Medical Association [On-line guidelines]. Available online at http://www.albertadoctors.org/resources/endocrinology.html.

Lobo, R. and Carmina, E. (2000 June 20). The Importance of Diagnosing the Polycystic Ovary Syndrome. Annals of Internal Medicine 2000;132:989-993 [On-line Journal]. Available online at http://www.annals.org/issues/v132n12/full/200006200-00010.html.

Polycystic ovary syndrome (2002). Hendrick Health System, AccessMed Health Information Library [On-line information]. Available online at http://www.hendrickhealth.org/healthy/index.htm.

Smith Waddell, R. (2000). PCOS Frequently Asked Questions. InterNational Council on Infertility, Information Dissemination (INCIID) [On-line information]. Available online at http://www.inciid.org/faq/pcos2.html.

Wozznicki, K. (2003 February 3). An Ovarian Link To Diabetes. MedlinePlus Health Information [On-line Article, United Press International Science News]. Available online at http://www.nlm.nih.gov/medlineplus/news/fullstory_11520.html.

Chen, P. (2002 February 7, Updated). Stein-Leventhal syndrome. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000369.htm.

Polycystic Ovary Syndrome (PCOS). The Hormone Foundation [On-line information]. Available online at http://www.hormone.org/learn/pcos.html.

Polycystic Ovary Syndrome (PCOS) (2001 April). The National Women’s Health Information Center, 4Woman.gov [On-line information]. Available online at http://www.4woman.gov/faq/pcos.htm.

Hunter, M. and Sterrett, J. (2000 September 1). Polycystic Ovary Syndrome: It’s Not Just Infertility. American Family Physician [On-line journal]. Available online at http://www.aafp.org/afp/20000901/1079.html.

#2023: Polycystic Ovary Evaluation. Specialty Laboratories Test Information [On-line information]. Available online at http://www.specialtylabs.com/test/details.asp?id=2023.

Adrenal Gland Disorders. The Merck Manual of Medical Information–Home Edition, Section 13. Hormonal Disorders, Chapter 146 [On-line information]. Available online at http://www.merck.com/mrkshared/mmanual_home/sec13/146.jsp.

Berga, S. (2003 January 23). Weight Loss Improves Reproduction and Insulin Levels in Women With Polycystic Ovary Syndrome. AMA Science News Media Briefings [On-line press release]. Available online at http://www.ama-assn.org/ama/pub/article/4197-7204.html.

Ehrmann, D.A. (2005 March 24). Polycystic Ovary Syndrome. New England Journal of Medicine 2005,352: 1223-1236.

(Updated 2010 March 17). Polycystic Ovary Syndrome (PCOS), Frequently Asked Questions. National Women’s Health Information Center [On-line information]. Available online at http://womenshealth.gov/faq/polycystic-ovary-syndrome.cfm. Accessed January 2011.

Ferry, R. (Updated 2010 April 27). Polycystic Ovarian Syndrome. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/924698-overview. Accessed January 2011.

Meikle, W. and Roberts, W. (Updated 2010 June). Polycystic Ovarian Syndrome. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/PCOS.html. Accessed January 2011.

Mayo Clinic Staff (Updated 2009 December 8). Polycystic Ovarian Syndrome. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/polycystic-ovary-syndrome/DS00423. Accessed January 2011.

Moran, L. et. al. (2010 March 11). Polycystic Ovary Syndrome and Weight Management. Medscape Today from Women’s Health. 2010;6(2):271-283. [On-line information]. Available online at http://www.medscape.com/viewarticle/717899. Accessed January 2011.

Pinkerton, J. (Revised 2010 January). Polycystic Ovary Syndrome (Hyperandrogenic Chronic Anovulation). Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merckmanuals.com/professional/sec18/ch244/ch244e.html. Accessed January 2011.

Eisenberg, E. (2010 March 17). Polycystic Ovary Syndrome (PCOS), Frequently Asked Questions. National Women’s Health Information Center [On-line information]. Available online at http://womenshealth.gov/faq/polycystic-ovary-syndrome.cfm. Accessed September 2010.

Storck, S. (Updated 2010 March 31). Polycystic ovary syndrome. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000369.htm. Accessed September 2010.

(Updated 2009 September 4). Polycystic Ovarian Syndrome. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/256806-overview. Accessed September 2010.

Cahill, D. Polycystic ovary syndrome (PCOS). Netdoctor. Available online at http://www.netdoctor.co.uk/womenshealth/facts/pcos.htm. Accessed September 2010.

Azziz R, Carmina E, Dewailly D, et. Al. The Androgen Excess and PCOS Society criteria for the polycystic ovary syndrome: the complete task force report. Fertility and Sterility 91:456-488, 2009. Available online through http://www.ae-society.org/

(September 3, 2014) Mayo Clinic. Diseases and Conditions. Polycystic ovary syndrome (PCOS). Available online at http://www.mayoclinic.org/diseases-conditions/pcos/basics/definition/con-20028841 through http://www.mayoclinic.org. Accessed April 2015.

Sheehan, Michael T., 2004. Polycystic Ovarian Syndrome: Diagnosis and Management. Clinical Medicine and Research. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1069067/ through http://www.ncbi.nlm.nih.gov. Accessed April 2015.

The American College of Obstetricians and Gynecologists. Polycystic Ovary Syndrome FAQ. Available online at http://www.acog.org/~/media/For%20Patients/faq121.pdf through http://www.acog.org. Accessed April 2015.

Gambineri A., et. al. Feb 2004. Clinical Endocrinology. Available online at http://www.ncbi.nlm.nih.gov/pubmed/14725687 through http://www.ncbi.nlm.nih.gov/pubmed. Accessed April 2015.

(October 8, 2014) Diane E. Judge. A Guide to Polycystic Ovary Syndrome. JournalWatch. Available online at http://www.jwatch.org/na35848/2014/10/08/guide-polycystic-ovary-syndrome?query=etoc_jwwomen through http://www.jwatch.org. Accessed April 2015.

(October 8, 2014) Robert L. Barbieri. Polycystic Ovary Syndrome: Diagnosis and Management. JournalWatch. Available online at http://www.jwatch.org/na35755/2014/10/08/polycystic-ovary-syndrome-diagnosis-and-management?query=etoc_jwwomen through http://www.jwatch.org. Accessed April 2015.

(Updated Sep 29, 2014) Lucidi R. Polycystic Ovarian Syndrome. Medscape Reference. Available online at http://emedicine.medscape.com/article/256806-overview#a0101 through http://emedicine.medscape.com. Accessed April 2015.

(November 04, 2013) Jenni Laidman. PCOS: Endocrine Society Issues New Guidelines. Medscape Medical News. Available online at http://www.medscape.com/viewarticle/813810. Accessed April 2014.

(May 2013) Meriggiola C, Zamah M. PCOS. Hormone Health Network. Available online at http://www.hormone.org/diseases-and-conditions/womens-health/polycystic-ovary-syndrome. Accessed April 2014.

(Reviewed May 2013) Eunice Kennedy Shriver National Institute of Child Health & Human Development. Does PCOS affect pregnancy? Available online at http://www.nichd.nih.gov/health/topics/PCOS/conditioninfo/Pages/pregnancy.aspx. Accessed April 2015.