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

Diagnostic Criteria for Polycystic Ovary Syndrome (PCOS)

The diagnosis of PCOS should be based on the Rotterdam criteria, which require the presence of at least two of the following three criteria: oligo/anovulation, clinical or biochemical hyperandrogenism, and polycystic ovary morphology on ultrasound, after excluding other etiologies. 1

Rotterdam Diagnostic Criteria in Detail

The Rotterdam criteria established in 2003 remain the standard for PCOS diagnosis 1, 2. To diagnose PCOS, a patient must have at least two of these three features:

1. Oligo/anovulation: Manifests as irregular menstrual cycles, amenorrhea, or long cycles
2. Hyperandrogenism: Can be clinical (hirsutism, acne, male-pattern baldness) and/or biochemical (elevated testosterone levels)
3. Polycystic ovary morphology (PCOM): Defined by ultrasound findings

Age-Specific Diagnostic Considerations

Adolescents

• In adolescents, PCOS should be diagnosed based on:
  • Irregular menstruation AND
  • Clinical and/or biochemical hyperandrogenism 1, 3
• Ultrasound is NOT required or recommended for diagnosis in this age group due to poor specificity 1, 3
• Ultrasound should not be used for PCOS diagnosis in those with gynecological age <8 years (less than 8 years after menarche) due to high incidence of multi-follicular ovaries in this life stage 1

Ultrasound Criteria for PCOM

When using ultrasound to assess for polycystic ovary morphology, the following criteria should be applied:

• Follicle Number Per Ovary (FNPO): ≥20 follicles measuring 2-9mm in at least one ovary (sensitivity 84%, specificity 91%) 1
• Ovarian Volume (OV): >10 mL in at least one ovary (sensitivity 81%, specificity 81%) 1

Important considerations for ultrasound assessment:

• Transvaginal ultrasound is preferred for accurate assessment 1
• For transabdominal ultrasound, only ovarian volume (≥10 ml) should be used due to difficulty in reliably assessing follicle count 1
• Ultrasound should be performed when ovaries are quiescent (no dominant follicles, corpus luteum, or cysts) 1

Clinical and Laboratory Evaluation

A comprehensive PCOS evaluation should include:

• Menstrual history: Pattern, frequency, and regularity of cycles

• Assessment of hyperandrogenic symptoms: Hirsutism, acne, male-pattern hair loss

• Hormonal assessment:

  • Total or bioavailable testosterone
  • DHEAS
  • 17-hydroxyprogesterone
  • LH/FSH ratio (often >2 in PCOS) 1

• Metabolic screening:

  • Weight, height, BMI calculation
  • Waist circumference
  • Blood pressure
  • Fasting glucose/insulin ratio
  • 2-hour oral glucose tolerance test (especially if BMI >30 kg/m²) 1, 4
  • Fasting lipid profile (triglycerides, HDL cholesterol) 1, 4

Exclusion of Other Etiologies

Before confirming a PCOS diagnosis, it's essential to rule out other conditions that may present with similar features:

• Thyroid dysfunction
• Hyperprolactinemia
• Congenital adrenal hyperplasia
• Cushing's syndrome
• Androgen-secreting tumors

Phenotypic Variations

The Rotterdam criteria create four possible PCOS phenotypes 3, 2:

1. Hyperandrogenism + oligo/anovulation + PCOM (classic PCOS)
2. Hyperandrogenism + oligo/anovulation (classic non-PCOM)
3. Hyperandrogenism + PCOM (ovulatory PCOS)
4. Oligo/anovulation + PCOM (non-hyperandrogenic PCOS)

Common Pitfalls in PCOS Diagnosis

• Relying solely on ultrasound: Diagnosis requires at least two criteria, not just PCOM on ultrasound 1
• Inappropriate ultrasound timing: Performing ultrasound during active follicular development can lead to misdiagnosis 1
• Using ultrasound in young adolescents: Not recommended in those <8 years post-menarche 1
• Failing to exclude other disorders: Conditions mimicking PCOS must be ruled out 1, 2
• Using outdated ultrasound criteria: The threshold for follicle count has increased from ≥12 to ≥20 follicles with improved imaging technology 1, 4

By following these diagnostic criteria and being aware of the potential pitfalls, clinicians can accurately diagnose PCOS and initiate appropriate management strategies to address both reproductive and metabolic aspects of this complex condition.