What are the diagnostic criteria for Polycystic Ovary Syndrome (PCOS)?

From the Guidelines

Polycystic ovary syndrome (PCOS) should be diagnosed using the Rotterdam criteria, which requires at least two of three key features: irregular or absent menstrual periods (oligo/anovulation), clinical or biochemical signs of hyperandrogenism, and polycystic ovaries on ultrasound, with the exclusion of other relevant disorders 1. The diagnosis of PCOS is based on the presence of at least two of the following three criteria:

• Oligo- or anovulation
• Clinical and/or biochemical signs of hyperandrogenism
• Polycystic ovaries on ultrasound, defined as an excessive number (≥20) of 2–9 mm follicles per ovary (follicle number per ovary, FNPO) using the trans-vaginal route and a transducer frequency >8 MHz 1 Other conditions with similar symptoms must be excluded, including thyroid disorders, hyperprolactinemia, congenital adrenal hyperplasia, androgen-secreting tumors, and Cushing's syndrome, through blood tests to measure hormone levels, including testosterone, DHEAS, TSH, prolactin, and 17-hydroxyprogesterone 1. It is essential to note that the use of ultrasound in PCOS diagnosis is not recommended within 8 years of menarche, and age-specific cut-offs for both PCOM and AMH are needed, as levels of AMH and follicle numbers vary across the lifespan 1. The diagnosis of PCOS is crucial, as it increases the risk for metabolic complications, including insulin resistance, type 2 diabetes, and cardiovascular disease, which may require additional screening and management 1. Key considerations in the diagnosis of PCOS include:
• The exclusion of other relevant disorders
• The use of age-specific cut-offs for PCOM and AMH
• The limitations of ultrasound in diagnosing PCOS, particularly in adolescents
• The importance of clustering AMH with other features of PCOS and the relationship between AMH and long-term health outcomes 1

From the Research

PCOS Diagnosis Criteria

The diagnosis of Polycystic Ovary Syndrome (PCOS) is based on specific criteria, including:

• Menstrual cycle anomalies, such as amenorrhoea, oligomenorrhoea, or long cycles 2
• Clinical and/or biochemical hyperandrogenism 2, 3, 4
• Ultrasound appearance of polycystic ovaries, defined as the presence of at least 12 follicles in each ovary measuring 2-9 mm in diameter, and/or increase in ovary size >10 ml 2
• The presence of two of these three criteria is sufficient once all other diagnoses have been ruled out 2

Rotterdam Criteria

The Rotterdam classification is commonly used to define PCOS, and includes the following criteria:

• Oligoanovulation
• Hyperandrogenism
• Polycystic ovaries on ultrasonography 2, 3, 4 The diagnosis of PCOS is primarily clinical, based on the presence of at least two of the three Rotterdam criteria 4

Phenotypes of PCOS

There are four recognized phenotypes of PCOS, each with different long-term health and metabolic implications:

• Hyperandrogenism + oligo-anovulation + polycystic ovarian morphology
• Hyperandrogenism + oligo-anovulation
• Hyperandrogenism + polycystic ovarian morphology
• Oligo-anovulation + polycystic ovarian morphology 3

Evaluation and Diagnosis

The evaluation of patients suspected of having PCOS includes:

• A thorough history and physical examination
• Assessment for the presence of hirsutism
• Ovarian ultrasonography
• Hormonal testing to confirm hyperandrogenism and oligo-anovulation as needed, and to exclude similar or mimicking disorders 3, 4