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

Diagnosing Polycystic Ovary Syndrome (PCOS)

The diagnosis of PCOS requires at least two of three Rotterdam criteria: oligo/anovulation, clinical or biochemical hyperandrogenism, and polycystic ovary morphology (PCOM) on ultrasound. 1

Diagnostic Criteria

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

1. Oligo/anovulation:

   • Menstrual cycle length >35 days suggests chronic anovulation 1
   • Slightly irregular cycles (32-36 days) should be assessed for ovulatory dysfunction 2

2. Hyperandrogenism:

   • Clinical signs: Hirsutism, acne (especially severe or treatment-resistant), and alopecia 1, 2
   • Biochemical: Elevated total testosterone and free testosterone levels 1
     • Free testosterone measurement is more sensitive than total testosterone 2
     • Liquid chromatography with tandem mass spectrometry (LC-MS/MS) is the preferred method 1

3. Polycystic Ovary Morphology (PCOM):

   • Transvaginal ultrasound showing ≥20 follicles per ovary measuring 2-9mm and/or ovarian volume ≥10ml 1
   • FNPO (follicle number per ovary) is the most accurate diagnostic marker with 84% sensitivity and 91% specificity 3, 1
   • Ovarian volume can be used as an alternative with 81% sensitivity and 81% specificity 3, 1

Laboratory Evaluation

• Androgen assessment:

  • Total testosterone and free testosterone (by equilibrium dialysis or calculated using free androgen index) 1
  • Other androgens have relatively low diagnostic value 2

• Exclusion of other disorders:

  • Thyroid-stimulating hormone (TSH) to exclude thyroid disease 1
  • Prolactin to exclude hyperprolactinemia 1
  • 17-hydroxyprogesterone to exclude non-classic congenital adrenal hyperplasia 1, 2
  • Tests to exclude Cushing's syndrome, androgen-secreting tumors, primary ovarian failure, and acromegaly as appropriate 1

• Metabolic screening:

  • Two-hour oral glucose tolerance test with 75g glucose load 1
  • Fasting glucose level 1
  • Lipid profile (total cholesterol, LDL, HDL, triglycerides) 1

Special Considerations

Adolescents

• Diagnosis is particularly challenging in adolescents 2
• Menstrual irregularities are common in the first 2-3 years post-menarche 2
• Persistent oligomenorrhea beyond 2-3 years post-menarche suggests PCOS 2
• Ultrasound is not recommended as a first-line investigation in females <17 years 1, 2
• Hyperandrogenism is central to the presentation in adolescents 4

Ethnic Variations

• East Asian women may have a higher prevalence of metabolic syndrome despite lower BMI and less hyperandrogenic features 1

Diagnostic Pitfalls to Avoid

1. Relying solely on ultrasound: While PCOM is important, diagnosis requires at least two criteria. FNPO is the most accurate ultrasound marker, but ovarian volume can be used if follicle counts cannot be accurately obtained 3, 1

2. Inadequate androgen testing: Using inappropriate assays or reference ranges. Free testosterone is more sensitive than total testosterone and should ideally be measured using equilibrium dialysis techniques 2

3. Failure to exclude other disorders: PCOS is a diagnosis of exclusion. Other conditions causing similar symptoms must be ruled out 1, 5

4. Overlooking metabolic assessment: PCOS is associated with increased risk of type 2 diabetes, cardiovascular disease, and metabolic syndrome 1, 6

5. Misdiagnosis in adolescents: Normal pubertal changes can mimic PCOS features. Persistent symptoms beyond 2-3 years post-menarche are more indicative of PCOS 2

By following these diagnostic criteria and considering the special populations and potential pitfalls, clinicians can accurately diagnose PCOS and initiate appropriate management to address both reproductive and metabolic aspects of this common endocrine disorder.