How Is Polycystic Ovary Syndrome (PCOS) Diagnosed?

What to know about getting diagnosed with PCOS


Ever wonder what criteria your doctor used to diagnose you with PCOS or why it took so long to receive a diagnosis of PCOS? 

Despite being such a common endocrine disorder, PCOS is not well understood. Many health care professionals are still puzzled about how to properly diagnose it especially among the adolescent population. Part of the confusion starts with the diagnostic criteria itself.

In the past, there were two separate (but similar) diagnostic criteria used to diagnose PCOS: One set established by the National Institutes of Health (NIH) and another set of criteria agreed upon during an evidence-based workshop held in Rotterdam which expanded the NIH criteria.

The absence of definitive criteria for PCOS has made it difficult to diagnose and especially difficult to compare studies. 

In December 2012, after the NIH held an evidence-based methodology workshop on PCOS, it was recommended that the Rotterdam criteria be used to diagnose PCOS.

The Rotterdam Criteria for Diagnosing PCOS

According to this criteria, a woman must meet at least two of the following three criteria: 

1. Irregular and/or no ovulation

Basically, if a woman has 8 or fewer menstrual cycles each year, she meets this criteria.

Due to an imbalance of sex hormones (high levels of luteinizing hormone and androgens, like testosterone) women with PCOS tend to have irregular menstrual cycles or no menstrual cycle at all, for months at a time, affecting fertility and ovulation. For some women with PCOS, they may get a period several times each month, every few months, or not at all. Periods may often times be heavy and accompanied by large clots.

As a side note, a small percentage of women with PCOS can experience monthly menstrual cycles and still meet the diagnostic criteria.

2. High Androgen Levels

Your doctor should run blood work to test your levels of androgens. This includes total and free testosterone, as well as DHEA-sulfate. If levels come back high, this is one of the criteria for PCOS.

A physical evaluation can also show signs of high androgens. For instance, if you have acne, hair loss, excessive central body hair growth, these too are considered part of the diagnostic criteria. You don’t have to have both, high blood levels of androgens or clinical signs of it to meet this criteria; one is sufficient.

3. The presence of follicles on an ultrasound

A transvaginal ultrasound is sometimes performed to confirm a PCOS diagnosis. In this instance, an ultrasound probe is placed inside the vagina that can detect the presence of follicles. 

The revised Rotterdam criteria now define PCOS as the presence of 12 or more small (2 to 9 mm) follicles in each ovary. These follicles are sometimes referred to as cysts (hence the name poly “cystic” ovary syndrome) and resemble a string of pearls. The follicles are a result of the hormonal imbalance, not the cause of it.

However, to complicate matters, there are many women who have follicles on their ovaries who don’t have PCOS, and many women who have been diagnosed with PCOS who do not have any follicles. The recommendation has been made to change the name of PCOS to one that represents the metabolic issues of PCOS, and moves away from the reproductive side that includes the word ‘cysts’.

4. Exclusion of all other conditions

PCOS is a condition of exclusion. This means that despite meeting at least two of the above mentioned criteria, other medical conditions need to be ruled out. For example, congenital adrenal hyperplasia (CAH) is a medical condition that also causes high testosterone. High prolactin levels can affect ovulation.

Evidenced-based Methodology Workshop Executive Summary. Washington D.C.: National Institutes of Health; December 2012.

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