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

Diagnostic Criteria for Polycystic Ovary Syndrome (PCOS)

PCOS is diagnosed using the Rotterdam criteria, which require at least 2 of 3 features: (1) oligo- or anovulation, (2) clinical and/or biochemical hyperandrogenism, and (3) polycystic ovarian morphology on ultrasound, after excluding other disorders. 1, 2

Core Diagnostic Framework

The Rotterdam criteria create four distinct phenotypes by requiring any two of three features 3, 4:

• Hyperandrogenism (clinical or biochemical)
• Ovulatory dysfunction (oligomenorrhea, amenorrhea, or cycles >35 days)
• Polycystic ovarian morphology (PCOM) on ultrasound

Clinical Assessment Components

Document the following specific elements 1:

• Menstrual history: Cycle length >35 days indicates chronic anovulation 1
• Signs of hyperandrogenism: Acne, male-pattern balding, hirsutism, clitoromegaly 1
• Anthropometric measurements: BMI and waist-hip ratio 1
• Medication review: Exclude exogenous androgen use 1
• Family history: Cardiovascular disease and diabetes 1
• Lifestyle factors: Diet, exercise, alcohol, smoking 1

Biochemical Hyperandrogenism Testing

Total testosterone measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the preferred first-line test, with 74% sensitivity and 86% specificity. 1, 5

Androgen Testing Hierarchy

1. Total testosterone (TT): Single best initial marker (74% sensitivity, 86% specificity) 1

   • LC-MS/MS method provides superior accuracy (92% specificity vs 78% for immunoassay) 1
   • Direct immunoassays are inadequate and should be avoided 5

2. Calculated free testosterone (cFT): Highest sensitivity at 89% with 83% specificity 1

   • Calculate using Vermeulen equation from high-quality TT and SHBG measurements 1

3. Free androgen index (FAI): 78% sensitivity, 85% specificity 1, 5

   • Use caution when SHBG <30 nmol/L 1

4. Androstenedione (A4): 75% sensitivity, 71% specificity 1

   • Particularly useful when SHBG is low 1

5. DHEAS: 75% sensitivity, 67% specificity 1

   • Most reliable for adrenal androgen production, especially in women <30 years 1

Ultrasound Criteria for PCOM

Follicle number per ovary (FNPO) ≥20 follicles is the gold standard ultrasonographic marker, with 87.64% sensitivity and 93.74% specificity. 6, 1

Ultrasound Technical Specifications

• Transvaginal approach: Use ≥8 MHz transducer frequency for optimal resolution in adults 1
• Primary marker: FNPO ≥20 follicles per ovary 6, 1
• Alternative markers when accurate follicle counting is impossible 6:
  • Ovarian volume (OV) >10 mL (81% sensitivity, 81% specificity) 6, 1
  • Follicle number per single cross-section (FNPS) (81% sensitivity, 83% specificity) 6

Critical Pitfall: Age-Specific Considerations

In adolescents (<20 years, at least 1 year post-menarche), ultrasound should NOT be used as a primary diagnostic criterion due to high false-positive rates from normal multi-follicular ovaries. 1, 5, 4

• Adolescent diagnosis requires BOTH: Hyperandrogenism AND irregular cycles 1, 4
• Ovarian morphology is excluded due to poor specificity in this age group 4
• Biochemical hyperandrogenism (elevated free testosterone and FAI) provides necessary confirmation 5

Mandatory Exclusion of Other Disorders

Before confirming PCOS diagnosis, exclude 1, 2:

• Cushing's syndrome: Buffalo hump, moon facies, hypertension, abdominal striae 1
• Androgen-secreting tumors: Rapid onset, severe hyperandrogenism 1
• Non-classic congenital adrenal hyperplasia 1
• Thyroid disease and prolactin disorders 1
• Primary hypothalamic amenorrhea and primary ovarian failure 1
• Acromegaly and genetic defects in insulin action 1

Metabolic Screening Requirements

All women diagnosed with PCOS must be screened for type 2 diabetes, glucose intolerance, and dyslipidemia. 1

Obtain the following 1, 7:

• Fasting plasma glucose and consider oral glucose tolerance test (OGTT) if BMI >30 kg/m² 7
• Fasting lipid profile: Triglycerides and HDL cholesterol 1, 7
• Blood pressure measurement 7
• Waist circumference 7

Geographic and Methodological Considerations

Studies using Rotterdam criteria show improved sensitivity for FNPO 6. Geographic variations exist, with North American studies showing lower diagnostic accuracy compared to Asian (FNPO sensitivity) and European studies (OV specificity) 6. These differences may reflect variations in age, BMI, and phenotypic expression across populations 6.

Emerging Diagnostic Tools

Anti-Müllerian Hormone (AMH) shows promise as an alternative to ultrasound for PCOM detection, with significantly higher levels in PCOS patients 1. However, current limitations include lack of standardization across assays and absence of established cut-offs, preventing its routine clinical use 1.