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

The Rotterdam criteria have been widely accepted as the standard for PCOS diagnosis 1, 2, 3. To establish a diagnosis, a patient must have at least two of these three features:

1. Oligo/anovulation:

   • Menstrual cycle anomalies
   • Amenorrhea, oligomenorrhea (cycles >35 days)
   • Long or irregular cycles

2. Hyperandrogenism:

   • Clinical manifestations: hirsutism, acne, male-pattern alopecia
   • Biochemical evidence: elevated free testosterone (preferably measured through equilibrium dialysis techniques as more sensitive than total testosterone) 4

3. Polycystic Ovary Morphology (PCOM) on ultrasound:

   • Presence of ≥20 follicles measuring 2-9mm in at least one ovary (Follicle Number Per Ovary - FNPO) - most accurate marker with 84% sensitivity and 91% specificity 1
   • OR ovarian volume >10 mL in at least one ovary (81% sensitivity, 81% specificity) 1, 3

Age-Specific Considerations

Adolescents

• PCOS diagnosis in adolescents should be based on:
  • Irregular menstruation (persistent oligomenorrhea 2-3 years post-menarche)
  • Clinical and/or biochemical hyperandrogenism
  • Ultrasound is NOT required or recommended for diagnosis in this age group 1, 4
• Caution: Many features of PCOS (acne, menstrual irregularities, hyperinsulinemia) are common in normal puberty 4

Adult Women

• Full Rotterdam criteria apply
• Transvaginal ultrasound is preferred for accurate assessment of PCOM 1
• For transabdominal ultrasound, only ovarian volume (≥10 ml) should be used due to difficulty in reliably assessing follicle count 1

Exclusion of Other Etiologies

Before confirming PCOS diagnosis, other conditions that can cause similar symptoms must be excluded:

• Thyroid dysfunction
• Hyperprolactinemia
• Non-classic congenital adrenal hyperplasia
• Androgen-secreting tumors
• Cushing's syndrome

Clinical Evaluation Components

1. Detailed history:

   • Menstrual patterns
   • Hyperandrogenic symptoms (onset and progression)
   • Family history of cardiovascular disease and diabetes
   • Symptoms of insulin resistance

2. Physical examination:

   • Weight, height, BMI calculation
   • Waist circumference
   • Blood pressure
   • Assessment of hirsutism, acne, and alopecia patterns

3. Laboratory evaluation:

   • Hormonal assessment:

     • Free testosterone (preferred) or total testosterone
     • DHEAS
     • 17-hydroxyprogesterone
     • LH/FSH ratio (often >2 in PCOS) 1

   • Metabolic screening:

     • Fasting glucose and insulin
     • Lipid profile
     • Oral glucose tolerance test (recommended if BMI >30 kg/m²) 3

Diagnostic Pitfalls and Caveats

• Ultrasound should be performed when ovaries are quiescent (no dominant follicles, corpus luteum, or cysts) to ensure accurate diagnosis 1
• 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
• Severe acne resistant to standard treatments may indicate PCOS (up to 40% likelihood) 4
• Hair loss patterns are variable but typically affect vertex, crown or show diffuse pattern; more severe hyperandrogenemia may cause bitemporal hair loss and loss of frontal hairline 4
• The Rotterdam criteria create additional phenotypes of PCOS compared to older definitions, including women with hyperandrogenism and polycystic ovaries but normal ovulatory function, and women with ovulatory dysfunction and polycystic ovaries but no hyperandrogenism 2

PCOS diagnosis has significant implications for long-term health risks, including increased risk of endometrial cancer, metabolic disorders, cardiovascular disease, and psychological disorders 1, making accurate diagnosis essential for appropriate management and follow-up.