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

Diagnostic Criteria for Polycystic Ovary Syndrome (PCOS)

The diagnosis of PCOS requires the presence of at least two of the following three criteria: oligo- or anovulation, clinical and/or biochemical hyperandrogenism, and polycystic ovarian morphology on ultrasound, with the exclusion of other relevant disorders. 1, 2

Core Diagnostic Criteria (Rotterdam Criteria)

• PCOS diagnosis requires at least two of these three features:
  • Oligo- or anovulation (menstrual cycle length >35 days suggests chronic anovulation) 1, 3
  • Clinical and/or biochemical hyperandrogenism 1, 2
  • Polycystic ovarian morphology (PCOM) on ultrasound 1, 2

Clinical Assessment

• Document menstrual history, with cycle length >35 days suggesting chronic anovulation 1, 3
• Assess for clinical signs of hyperandrogenism:
  • Hirsutism (develops gradually and intensifies with weight gain) 1, 2
  • Acne (severe or resistant to treatment may indicate PCOS) 2
  • Male-pattern hair loss (variable patterns including vertex, crown, or diffuse) 1, 2
  • Clitoromegaly (more common in neoplastic virilizing states than PCOS) 2
• Calculate BMI and waist-hip ratio 1
• Review medication use, including exogenous androgens 1
• Obtain family history of cardiovascular disease and diabetes 1

Laboratory Evaluation

• Total testosterone (TT) is the most frequently abnormal biochemical marker (70% of PCOS cases) 4
• Free testosterone (FT) levels are more sensitive than total testosterone for establishing androgen excess 2
• Consider measuring androstenedione (abnormal in 53% of PCOS cases) 4
• LH/FSH ratio has low sensitivity (41-44%) and should not be used as a sole diagnostic criterion 4
• 17-hydroxyprogesterone to rule out non-classic congenital adrenal hyperplasia 2, 5
• Anti-Müllerian Hormone (AMH) is being investigated as a potential alternative to ultrasound for PCOM detection 1

Ultrasonographic Assessment

• Follicle number per ovary (FNPO) is the gold standard ultrasonographic marker for PCOS diagnosis in adult women 6, 1
  • FNPO ≥20 follicles has highest diagnostic accuracy (sensitivity: 84%, specificity: 91%) 6, 1
• Ovarian volume (OV) >10 mL is the threshold for increased ovary size 1
• Follicle number per single cross-section (FNPS) can be used when FNPO cannot be accurately obtained 6, 1
• Transvaginal ultrasound with ≥8 MHz transducer frequency is recommended for optimal resolution in adults 1
• Ultrasound is not recommended as a first-line investigation in adolescents (<17 years) due to poor specificity 1, 2

Differential Diagnosis

• Rule out conditions that may mimic PCOS:
  • Cushing's syndrome (buffalo hump, moon facies, hypertension, abdominal striae) 1, 5
  • Androgen-secreting tumors (rapid onset, severe hyperandrogenism) 1, 5
  • Non-classic congenital adrenal hyperplasia 1, 5
  • Thyroid disease and prolactin disorders 1
  • Primary hypothalamic amenorrhea and primary ovarian failure 1
  • Acromegaly and genetic defects in insulin action 1

Special Considerations for Adolescents

• Persistent oligomenorrhea 2-3 years beyond menarche predicts ongoing menstrual irregularities 2
• Diagnosis should be based on oligomenorrhea and/or biochemical evidence of oligo/anovulation 2
• Large, multicystic ovaries are common in adolescents, making ultrasound less useful 2
• There are major limitations to the sensitivity of testosterone assays in ranges applicable to young girls 2

Impact of Medications on Diagnosis

• Spironolactone can affect diagnostic parameters by:
  • Decreasing serum testosterone levels 7
  • Improving menstrual regularity, which can mask oligo/amenorrhea 7
  • Reducing hirsutism scores 7
• If possible, conduct PCOS evaluation before initiating spironolactone therapy 7
• Consider a 2-4 week washout period before hormonal evaluation if patient is already on spironolactone 7

Common Pitfalls in PCOS Diagnosis

• Relying solely on LH/FSH ratio, which has low sensitivity (41-44%) 4
• Using ultrasound as first-line investigation in adolescents <17 years 1, 2
• Failing to exclude other conditions that mimic PCOS 1, 5
• Not accounting for the effects of medications like spironolactone on diagnostic parameters 7
• Using inappropriate testosterone assays with poor sensitivity in the female range 2

By following these diagnostic criteria and avoiding common pitfalls, clinicians can accurately diagnose PCOS and initiate appropriate management to improve morbidity, mortality, and quality of life outcomes for affected women.