PCOS - The Path to Diagnosis

Posted on August 15, 2018

No one test is conclusive for a diagnosis of polycystic ovary syndrome (PCOS). PCOS is generally diagnosed through a combination of a physical examination, family history, blood tests, and imaging scans. Diagnosis is usually performed by a family doctor or a gynecologist (specialist in the female reproductive system). Women with PCOS may also be referred to a dermatologist (specialist in skin conditions) or an endocrinologist (specialist in gland and hormone disease), depending on symptoms.

How is PCOS diagnosed?

The guidelines for diagnosing PCOS in adults are known as the Rotterdam criteria. According to these guidelines, a woman must meet at least two of three main criteria:

  • Polycystic ovaries

Enlarged ovaries, or an ovary with at least 12 or more follicles. Follicles are small fluid-filled sacs containing an egg. Normally, about five follicles develop each month.

  • Hyperandrogenism

Elevated levels of androgens (called male hormones). Androgen levels may be assessed with blood tests or by evaluating symptoms of excess androgen, such as excess body or facial hair (hirsutism), male-pattern baldness, or severe acne.

  • Irregular periods

Menstrual bleeds occurring too frequently (every three weeks or less) or infrequently (every five weeks or more), heavy bleeding, or a lack of ovulation. In some cases, there may be no period at all.

PCOS is often diagnosed in adolescence, as symptoms generally begin with the onset of menstruation. However, in adolescents, the absence of hyperandrogenism rules out a conclusive diagnosis of PCOS. Adolescent girls with irregular periods and polycystic ovaries but without signs of androgen imbalance may be regularly followed by a doctor to check whether signs of hyperandrogenism develop over time.

Some doctors diagnose women with a specific type of PCOS, while others do not.

Tests and what they show

Medical and family history

The doctor will take a thorough patient history, asking about when menstruation first began, how frequent periods have been, and how long they tend to last, among other details.

Having a family history of PCOS is a risk factor for developing the condition. Therefore, your doctor will ask whether your mother or sisters have the condition. They may also ask about female relatives with type 2 diabetes, since the condition is a common complication of PCOS.

Pelvic exam

Your doctor will do a visual and manual examination of your reproductive organs. They will look and feel for growths, swollen areas, or other irregularities.


Ultrasound imaging, which uses high-frequency sound waves and a computer to visualize them, is an important diagnostic tool for PCOS. Ultrasounds are painless and do not expose women to harmful radiation. There are two types of ultrasound: abdominal and transvaginal. In an abdominal ultrasound, your doctor or a technician will put ultrasound gel on your abdomen and move a probe over it. The sound waves coming from the probe are transmitted through the gel and the probe collects the waves that bounce back. The computer creates an image, allowing your doctor to look at your ovaries and check for cysts or abnormal enlargement. Abdominal ultrasounds are less accurate, but they are preferred for girls or women who have not been sexually active.

For women who are or have been sexually active, a transvaginal ultrasound will be performed instead. The ultrasound probe is a wand with a sensor on top that is inserted into your vagina. This method uses the same ultrasound technique, but can provide a much clearer picture, since sound waves do not have to travel through the abdominal wall before reaching the ovaries.

Ultrasound imaging can show whether the ovaries are normal, enlarged, or polycystic.

Lab tests

Blood tests are used to check hormone levels, providing key evidence to support or rule out a diagnosis of PCOS. Blood tests can show imbalances in levels of:

  • Testosterone and other androgens
  • Estrogen
  • Luteinizing hormone (LH)
  • Follicle-stimulating hormone (FSH)
  • Thyroid hormone
  • Prolactin

Blood tests can also be used to check blood glucose and cholesterol levels. These tests are more likely to be performed after a diagnosis of PCOS has been confirmed.


External resources

myPCOSteam resources


Which conditions have similar symptoms to PCOS?

Several conditions can cause symptoms similar to those seen in PCOS. Doctors considering a diagnosis of PCOS may try to rule out congenital adrenal hyperplasia, nonclassic adrenal hyperplasia, Cushing syndrome, androgen-secreting tumors, idiopathic hyperandrogenism, and idiopathic hirsutism.

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