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

Rotterdam Criteria (2003)

The most widely accepted diagnostic criteria for PCOS are the Rotterdam criteria, which require at least two of the following three features:

• Oligo- or anovulation: Characterized by menstrual irregularity with cycle length >35 days suggesting chronic anovulation 3, 4
• Clinical and/or biochemical hyperandrogenism:
  • Clinical signs include hirsutism, acne, alopecia, and rarely clitoromegaly 3, 4
  • Biochemical assessment should ideally include free testosterone levels measured through equilibrium dialysis techniques, which are more sensitive than total testosterone 4
• Polycystic ovarian morphology (PCOM) on ultrasound: 1
  • Follicle number per ovary (FNPO) ≥20 follicles (highest sensitivity 87.64% and specificity 93.74%) 3
  • Ovarian volume (OV) >10 mL 3

Ultrasound Assessment Considerations

• FNPO is considered the gold standard ultrasonographic marker for PCOS diagnosis in adult women 1
• Transvaginal ultrasound with ≥8 MHz transducer frequency is recommended for optimal resolution in adults 3
• Ultrasound is not recommended as a first-line investigation in adolescents (<17 years) due to poor specificity 3, 4
• Alternative markers when FNPO cannot be accurately obtained include: 1
  • Ovarian volume (OV)
  • Follicle number per single cross-section (FNPS)

Special Considerations for Adolescents

• Diagnosis in adolescents is particularly challenging due to developmental issues 4
• Persistent oligomenorrhea 2-3 years beyond menarche suggests underlying ovarian or adrenal dysfunction 4
• Large, multicystic ovaries are common in adolescents, making ultrasound less useful in girls <17 years 4
• Diagnosis should be based on oligomenorrhea and/or biochemical evidence of oligo/anovulation 4

Differential Diagnosis

Before confirming PCOS diagnosis, it's essential to exclude other disorders that may present with similar features:

• Cushing's syndrome (buffalo hump, moon facies, hypertension, abdominal striae) 3
• Androgen-secreting tumors (rapid onset, severe hyperandrogenism) 3
• Non-classic congenital adrenal hyperplasia 3
• Acromegaly and genetic defects in insulin action 3
• Primary hypothalamic amenorrhea and primary ovarian failure 3
• Thyroid disease and prolactin disorders 3

Emerging Diagnostic Considerations

• Anti-Müllerian Hormone (AMH) is being investigated as a potential alternative to ultrasound for PCOM detection 1
• AMH levels are significantly higher in women with PCOS compared to normal ovulatory women 1
• Current limitations for AMH include lack of standardization across assays and absence of established cut-offs 1

Clinical Approach to Diagnosis

1. Document menstrual history: Cycle length >35 days suggests chronic anovulation 3
2. Assess for clinical hyperandrogenism: Look for acne, balding, hirsutism, and clitoromegaly 3
3. Review medication use: Including exogenous androgens 3
4. Calculate BMI and waist-hip ratio: Obesity is common but not required for diagnosis 3
5. Laboratory assessment: Free testosterone levels are more sensitive than total testosterone 4
6. Ultrasound evaluation: FNPO ≥20 follicles or ovarian volume >10 mL in adults 3
7. Rule out other disorders: Through appropriate testing based on clinical suspicion 3

PCOS is a heterogeneous condition with significant implications for reproductive, metabolic, and psychological health. Accurate diagnosis using standardized criteria is essential for appropriate management and to address long-term health risks.