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Polycystic Ovary Syndrome (PCOS)


JoAnn V. Pinkerton

, MD, University of Virginia Health System

Full review/revision Feb 2021 | Modified Sep 2022
Topic Resources

Polycystic ovary syndrome is characterized by slight obesity, irregular or no menstrual periods, and symptoms caused by high levels of male hormones (androgens). It involves disruption of the menstrual cycle and a tendency to have high levels of male hormones (androgens).

  • Typically, women are obese and develop acne and masculine characteristics—the voice deepens, breast size decreases, and excess body hair appears.

  • Doctors often base the diagnosis on symptoms, but blood tests to measure hormone levels and ultrasonography may also be done.

  • Exercise, weight loss, and estrogen plus a progestin or progesterone or a progestin alone may help reduce symptoms (including excess body hair) and restore hormone levels to normal.

  • If women wish to become pregnant, losing weight and taking clomiphene, sometimes with metformin, may stimulate release of an egg.

Polycystic ovary syndrome affects about 5 to 10% of women. In the United States, it is the most common cause of infertility.

This syndrome gets its name from the many fluid-filled sacs (cysts) that often develop in the ovaries, causing them to enlarge.

Did You Know...

  • Polycystic ovary syndrome is the most common cause of infertility in the United States.

In many women with polycystic ovary syndrome, the body’s cells resist the effects of insulin (called insulin resistance or sometimes prediabetes). Insulin helps sugar (glucose) pass into cells so that they can use it for energy. When cells resist its effects, sugar accumulates in the blood, and the pancreas produces more insulin to try to lower sugar levels in the blood. If insulin resistance becomes moderate or severe, diabetes is diagnosed.

Causes of PCOS

What causes polycystic ovary syndrome is not clear. Some evidence suggests that the enzyme controlling the production of male hormones malfunctions. As a result, the production of male hormones (androgens) increases.

High levels of male hormones increase the risk of metabolic syndrome Metabolic Syndrome Metabolic syndrome is characterized by a large waist circumference (due to excess abdominal fat), high blood pressure, resistance to the effects of insulin (insulin resistance) or diabetes,... read more (with high blood pressure, high cholesterol levels, and resistance to the effects of insulin). If male hormone levels remain high, the risk of diabetes, heart and blood vessel disorders (including atherosclerosis Atherosclerosis Atherosclerosis is a condition in which patchy deposits of fatty material (atheromas or atherosclerotic plaques) develop in the walls of medium-sized and large arteries, leading to reduced or... read more Atherosclerosis and coronary artery disease Overview of Coronary Artery Disease (CAD) Coronary artery disease is a condition in which the blood supply to the heart muscle is partially or completely blocked. The heart muscle needs a constant supply of oxygen-rich blood. The coronary... read more Overview of Coronary Artery Disease (CAD) ), and high blood pressure is increased. Also, some of the male hormones may be converted to estrogen, increasing estrogen levels. Not enough progesterone is produced to balance the increased level of estrogen. If this situation continues a long time, the lining of the uterus (endometrium) may become extremely thick (a condition called endometrial hyperplasia). Also, the risk of cancer of the lining of the uterus Cancer of the Uterus The most common type of cancer of the uterus develops in the lining of the uterus (endometrium) and is called endometrial cancer. Endometrial cancer usually affects women after menopause. It... read more Cancer of the Uterus (endometrial cancer) may be increased.

Polycystic ovary syndrome may also increase the risk of nonalcoholic fatty liver disease Fatty Liver (abnormal accumulation of fats inside liver cells that is not related to alcohol consumption).

Symptoms of PCOS

Symptoms of polycystic ovary syndrome typically develop during puberty and worsen with time. Symptoms vary from woman to woman.

Typically, menstrual periods do not start at puberty, and the ovaries do not release an egg (that is, women do not ovulate) or release an egg irregularly. Women have irregular vaginal bleeding or no menstrual periods.

Women also develop symptoms related to the high levels of male hormones—called masculinization or virilization. Symptoms include acne, a deepened voice, a decrease in breast size, and an increase in muscle size and in body hair (hirsutism). Hair grows as it does in men (for example, on the chest and face) and may thin at the temples.

Most women with polycystic ovary syndrome are slightly obese, but some are thin. Producing too much insulin contributes to weight gain and makes losing weight difficult. Excess insulin due to insulin resistance may also cause skin in the armpits, on the nape of the neck, and in skinfolds to become dark and thick (a disorder called acanthosis nigricans).

Diagnosis of PCOS

  • A doctor's evaluation

  • Measurement of hormone levels

  • Ultrasonography

Often, the diagnosis of polycystic ovary syndrome is based on symptoms.

A pregnancy test is routinely done. Blood tests to measure levels of hormones such as follicle-stimulating hormone and male hormones are also done.

Ultrasonography is done to see whether the ovaries contain many cysts and to check for a tumor in an ovary or adrenal gland. These tumors can produce excess male hormones and thus cause the same symptoms as polycystic ovary syndrome. Transvaginal ultrasonography may be done to check for abnormalities in the ovaries. Transvaginal ultrasonography involves using a small handheld device inserted through the vagina to view the interior of the uterus.

In women with this syndrome, doctors measure blood pressure and usually levels of blood sugar and fats (lipids), such as cholesterol, to check for metabolic syndrome, which increases the risk of coronary artery disease.

Doctors may also do imaging tests to check for evidence of coronary artery disease. Imaging tests include coronary angiography (x-rays of arteries taken after a radiopaque contrast agent, which can be seen on x-rays, is injected into an artery) and computed tomography (CT) angiography (2- and 3-dimensional images of blood vessels taken after a radiopaque contrast agent is injected into a vein).

Often, a biopsy of the uterine lining (endometrial biopsy) is done to make sure no cancer is present, particularly if women have abnormal vaginal bleeding.

Treatment of PCOS

  • Exercise, dietary changes, and weight loss

  • Drugs, such as birth control pills, metformin, or spironolactone

  • Treatment of excess body hair and acne

The choice of treatment for polycystic ovary syndrome depends on the following:

  • Type and severity of symptoms

  • The woman’s age

  • Her plans regarding pregnancy

General measures

If insulin levels are high, lowering them may help. Exercising (at least 30 minutes a day) and reducing consumption of carbohydrates (in breads, pasta, potatoes, and sweets) can help lower insulin levels.

Weight loss may help with the following:

  • Lowering insulin levels enough that ovulation can begin

  • Increasing the chances of becoming pregnant

  • Making menstrual periods more regular

  • Reducing hair growth and the risk of thickening of the uterine lining

However, weight loss is unlikely to benefit normal-weight women with polycystic ovary syndrome.


Women who do not wish to become pregnant are usually given a birth control pill that contains only a progestin (a synthetic form of the female hormone progesterone), such as medroxyprogesterone, or one that contains estrogen and a progestin (a combination oral contraceptive). Either treatment may

  • Reduce the risk of endometrial cancer due to the high estrogen level

  • Make menstrual periods more regular

  • Help lower the levels of male hormones

  • Slightly reduce excess body hair and acne

Metformin, which is used to treat type 2 diabetes, may be used to increase sensitivity to insulin so the body does not have to make as much insulin. This drug may help women lose weight, and ovulation and menstrual periods may resume. If women take metformin and do not wish to become pregnant, they should use birth control. Metformin has little or no effect on excess hair growth, acne, or infertility. When metformin is used, women need to periodically have blood tests to measure glucose (sugar) and to evaluate kidney and liver function.

Newer drugs that can help women with polycystic ovary syndrome lose weight include liraglutide (used to treat type 2 diabetes) and orlistat Drugs Drugs (used to treat obesity). Orlistat and inositols (which make insulin act more effectively) may reduce symptoms related to the high levels of male hormones (such as excess body hair) and lessen insulin resistance.

If women wish to become pregnant, losing weight may help. If it does not, clomiphene (a fertility drug) or letrozole is tried. These drugs stimulate ovulation. If these drugs are ineffective and the woman has insulin resistance, metformin may help because lowering insulin levels may trigger ovulation. If none of these drugs is effective, other fertility drugs may be tried. They include follicle-stimulating hormone (to stimulate the ovaries), a gonadotropin-releasing hormone (GnRH) agonists Drugs used to treat endometriosis Drugs used to treat endometriosis (to stimulate the release of follicle-stimulating hormone), and human chorionic gonadotropin (to trigger ovulation).

If fertility drugs are ineffective or if women do not wish to take them, surgery (called ovarian drilling) may be tried. It is done by laparoscopy. Doctors make smalls incisions just above or below the navel. They then insert a thin viewing tube (called a laparoscope) into the abdominal cavity through one incision. Through another incision, they insert special tools that use an electric current or laser to destroy small areas of the ovaries that produce male hormones (androgens). Thus, androgen production is decreased. Decreasing the high levels of androgens in women with polycystic ovary syndrome can help regulate menstrual cycles and improve the chances of pregnancy. General anesthesia is required.

Treatment of excess body hair

Treatment of excess body hair Treatment In men, the amount of body hair varies greatly (see also Overview of Hair Growth), but very few men are concerned enough about excess hair to see a doctor. In women, the amount of hair that... read more Treatment includes bleaching or removal by electrolysis, plucking, waxing, hair-removing liquids or creams (depilatories), or laser. No drug treatment for removing excess hair is ideal or completely effective. The following may help:

  • Eflornithine cream may help remove unwanted facial hair.

  • Oral contraceptives may help, but they must be taken for several months before any effect, which is often slight, can be seen.

  • Spironolactone, a drug that blocks the production and action of male hormones, can reduce the amount of unwanted body hair. Side effects include increased urine production and low blood pressure (sometimes causing fainting). Spironolactone may not be safe for a developing fetus, so sexually active women taking the drug are advised to use effective birth control methods.

  • Cyproterone, a strong progestin that blocks the action of male hormones, reduces the amount of unwanted body hair in 50 to 75% of affected women. It is used in many countries but is not approved in the United States.

Gonadotropin-releasing hormone agonists and antagonists are being studied as treatment for unwanted body hair. Both types of drugs inhibit the production of sex hormones by the ovaries. But both can cause bone loss and lead to osteoporosis.

Losing weight reduces production of androgens and thus may slow hair growth.

Treatment of acne

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