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How is PCOS diagnosed?

Learn how PCOS is diagnosed, when to see your doctor and how your doctor might test you for PCOS.

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There are a number of signs and symptoms women with PCOS can have. However, not every woman with PCOS will have every symptom, and each woman will be quite individual in her experience.

Criteria for a diagnosis of PCOS

A diagnosis of polycystic ovary syndrome can be made when at least two out of three of the following criteria are met:

  • The ovaries are 'polycystic' because:
    • 12 or more follicles are visible on one ovary, or
    • the size of one or both ovaries is increased
  • There are:
    • high levels of 'male' hormones (androgens) in the blood (hyperandrogenism)
    • symptoms suggesting an excess of androgens such as:
      • excess facial or body hair growth
      • scalp hair loss
      • acne
  • There is menstrual dysfunction such as:
    • lack of periods or menses (menstrual flow)
    • menstrual irregularity
    • lack of ovulation (where an egg is released)
PCOS diagnostic criteria3

With these criteria, a woman can be diagnosed with PCOS even if she has regular periods or normal androgen levels. This means women with PCOS can experience very different types of symptoms.

To make a correct diagnosis of PCOS, a number of other conditions that could cause similar symptoms of menstrual dysfunction need to be ruled out.

When to see your doctor

If you think you may have PCOS, you need to see your doctor.

Below are some of the tests your doctor may recommend to test for PCOS and to exclude other conditions. Not all tests are necessary for every woman.

Diagnosis & tests

Medical history & examination

As part of the diagnosis, your doctor will review your medical history and assess your physical symptoms, weight and BMI (body mass index).


An ultrasound of the uterus, ovaries and the pelvis can be carried out to identify whether there are any cysts on your ovaries and whether an ovary is enlarged.

A transvaginal ultrasound is a painless test with no radiation. It uses a pen–shaped probe with an ultrasound sensor on the tip, which is inserted into the vagina. This produces a much clearer picture than an abdominal ultrasound.

Transvaginal ultrasounds are only performed on women who have been sexually active, otherwise an abdominal scan is done where the ovaries are viewed from the outside through the stomach wall.

Blood tests

Hormonal blood tests

Blood tests are used to assess the levels of androgens in your body. Blood tests for androgens (such as testosterone) and free androgen index (FAI) are the best tests for diagnosing whether you have hyperandrogenism (high androgen levels).

Other blood tests that can be useful in identifying high androgen levels include:

  • sex hormone binding–globulin (SHBG)
  • dehydroepiandrosterone sulphate (DHEAS)
  • androstenedione

Blood tests may also be done to assess the levels of other reproductive hormones in your body as these may affect your menstruation. These may include testing your levels of:

  • oestradiol (oestrogen)
  • follicle stimulating hormone (FSH)
  • luteinising hormone (LH)

Blood tests to exclude other conditions that have similar symptoms to PCOS may measure the levels of:

  • thyroid stimulating hormone (TSH)
  • prolactin
  • hormones related to adrenal function (glands found above the kidney), e.g. 17-hydroxyprogesterone

Other tests

Assessing your risk of developing cardiovascular disease and diabetes is important when testing for PCOS because there are links between PCOS and insulin resistance and being overweight. Tests to assess these risks will measure:

  • cholesterol blood test
  • blood pressure
  • glucose metabolism/tolerance blood test

If you have PCOS you should have a cholesterol and glucose tolerance test every two years, and blood pressure should be checked every year. If you have risk factors such as a family history of diabetes or previous abnormal cholesterol tests, then these tests should be performed more frequently.

Tests for other conditions

Other conditions of the adrenal glands, ovaries or pituitary gland (a small gland attached to the brain that controls a number of hormones in the body) can be ruled out by other tests if necessary.

Testing adolescents for PCOS

In adolescents, menstrual cycles can be irregular for reasons unrelated to PCOS, especially in the first few years after periods start. It is best to wait until two years of irregular periods before assessing whether the cause is PCOS, unless there are other bothersome symptoms such as excess hair growth, acne or weight excess.

Testing for PCOS when you take an oral contraceptive pill

Taking the oral contraceptive pill changes reproductive hormone levels, so it is not possible to accurately measure your androgen and other hormone levels if you are on the pill. To accurately measure androgen levels for a PCOS diagnosis, you may need to stop the oral contraceptive pill for three months and, if necessary, use other forms of contraception during this time. Your doctor is the best one to advise you about this.

Last updated: 16 January 2020

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