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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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Identifying PCOS

PCOS can be a complex condition to identify because there are numerous symptoms, and you don’t have to have all of them to be diagnosed with PCOS. Very few women have the same set of symptoms, and the symptoms can change at different stages of your life.

The symptoms differ widely between women, but the three main areas they affect are:

  • fertility and reproductive health
  • metabolic health
  • psychological health.

Although there is no cure for PCOS, the good news is that PCOS is treatable. We know that our lifestyle (what we eat and how active we are) can worsen or improve the symptoms of PCOS. With support from your doctor and other health-care givers, there are many ways to manage your lifestyle and improve all aspects of PCOS.

Criteria for a diagnosis of PCOS

A diagnosis of PCOS can be made when at least two of the following three criteria are met:

1. Irregular periods or no periods

2. Higher levels of androgens are present in the blood (hyperandrogenism), shown by:

  • a blood test, OR
  • symptoms such as:
    • excess facial or body hair growth
    • scalp hair loss
    • acne.

3. Polycystic ovaries are visible on an ultrasound, meaning:

  • more than 20 follicles (partly developed eggs) are visible on one or both ovaries or
  • the size of one or both ovaries is increased (more than 10ml).

You do not need to have an ultrasound if you have criteria 1 and 2.

In women younger than 20 years, ultrasounds are not recommended. This means that irregular periods and hyperandrogenism need to be present for a diagnosis of PCOS to be made.

A number of other conditions that could cause similar symptoms of irregular periods or no periods need to be checked by your doctor and ruled out before a correct diagnosis of PCOS can be confirmed.

Group girls table smiling pcos booklet

PCOS booklet

Read more on PCOS in our booklet 'Understanding polycystic ovary syndrome: All you need to know'

When to see your doctor

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

Below are some of the tests your doctor might recommend to test for PCOS and to exclude other conditions. The signs and symptoms of PCOS can be similar to other conditions, so it is important to rule these out before a diagnosis of PCOS can be made.

Not all tests are necessary for every woman – tests will be suggested based on your individual symptoms.

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).

Blood tests

Hormonal blood tests

Blood tests are used to assess the levels of androgens in your body. Blood tests for 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 also might be done to assess the levels of other reproductive hormones in your body, as these can also affect your periods. These can include testing your levels of:

  • oestradiol (oestrogen, the main female sex hormone)
  • follicle-stimulating hormone (FSH)
  • luteinising hormone (LH).

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

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


An ultrasound might be carried out to provide an image (picture) of the uterus, ovaries and the pelvis. The image shows whether there are any ‘cysts’ (partly developed eggs) on your ovaries and whether an ovary is enlarged. It is also useful to assess the lining of the womb (endometrium), which may become thickened if periods are very irregular, which is a risk factor for womb cancer.

An ultrasound is not needed if periods are irregular and there are signs or measurements of high levels of androgens, and the woman is aged less than 20 years. If there are very high levels of androgens or an unusual set of symptoms (for example, severe scalp hair loss or excess hair growth, or failure to develop periods altogether) then an ultrasound might still be necessary.

Transvaginal ultrasound

Transvaginal ultrasounds are performed only on women who have been sexually active, otherwise an abdominal scan is done. 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.

Abdominal ultrasound

In an abdominal ultrasound, the ovaries are viewed from the outside through the stomach wall.

Other tests

Assessing your risk of developing cardiovascular (heart) disease and diabetes is important when testing for PCOS because there are links between PCOS, insulin resistance and being overweight. Tests to assess these risks can include:

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

If you have PCOS, you will need a cholesterol and diabetes test every 1-3 years, and a blood pressure check every year. If you have risk factors such as a family history of diabetes or previous abnormal cholesterol tests, you will need these tests more often.

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PCOS Group of young women

Tests for other conditions

Other tests might be needed to rule out 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).

Testing adolescents for PCOS

It is difficult to diagnose PCOS in young women during the first few years after their periods (menstruation) commence. In adolescents, menstrual cycles can be irregular for reasons unrelated to PCOS, especially in the first few years after periods start. In the first year, periods are often irregular, and by the second year periods normally settle into a regular pattern.

In young women with PCOS, however, this does not happen. Instead, periods are either very close together (fewer than 21 days) or far apart (more than 45 days). If this irregularity continues after three years, this suggests PCOS might be the cause.

When to test

Because periods can be irregular for other reasons during the first few years, it is best to wait until after three years of irregular periods before assessing whether the cause is PCOS. However, if there are other bothersome symptoms, such as excess hair growth, acne or weight excess, an assessment for PCOS can be made earlier.

In some adolescents, a number of the features of PCOS are present, but it is still not possible to make a definite diagnosis of PCOS. These young women are regarded as ‘at risk’ of PCOS, and they will have further follow-up assessments by their doctor.

Testing for PCOS when you take an oral contraceptive pill

Taking the oral contraceptive pill changes your reproductive hormone levels, so it is not possible to accurately measure your hormone levels if you are on the pill. To accurately measure androgen levels for a PCOS diagnosis, you might 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.

0919 jh factsheet pcos THUMB

PCOS fact sheet

Includes information on how to improve PCOS symptoms and manage your long-term health.

This web page is designed to be informative and educational. It is not intended to provide specific medical advice or replace advice from your health practitioner. The information above is based on current medical knowledge, evidence and practice as at September 2019.


Last updated: 10 March 2022 | Last reviewed: 01 September 2019

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