What is the evaluation process for polycystic ovary syndrome (PCOS)?

Evaluation for Polycystic Ovary Syndrome (PCOS)

Diagnostic Criteria

PCOS diagnosis requires at least 2 of 3 Rotterdam criteria: hyperandrogenism (clinical or biochemical), ovulatory dysfunction, and polycystic ovarian morphology on ultrasound, after excluding other disorders. 1, 2, 3

Clinical Assessment

History

• Menstrual history: Cycle length >35 days indicates chronic anovulation 1
• Onset and duration of androgen excess signs (acne, hirsutism, male-pattern baldness) 1
• Medication review: Document use of exogenous androgens or other hormonal medications 1
• Family history: Cardiovascular disease, diabetes, and similar PCOS symptoms in relatives 1
• Lifestyle factors: Diet, exercise patterns, alcohol use, smoking 1

Physical Examination

• Signs of hyperandrogenism: Acne, hirsutism (use Ferriman-Gallwey score), male-pattern balding, clitoromegaly 1
• Body measurements: Calculate BMI and waist-hip ratio 1
• Exclude Cushing's syndrome: Look for buffalo hump, moon facies, hypertension, abdominal striae 1
• Rule out virilization: Rapid onset or severe hyperandrogenism suggests androgen-secreting tumor requiring immediate evaluation 1, 3

Laboratory Testing

First-Line Androgen Assessment

Total testosterone (TT) is the single best initial biochemical marker, with 74% sensitivity and 86% specificity. 4, 2, 5

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the preferred measurement method over direct immunoassays, offering superior specificity (92% vs 78%) and sensitivity (71% vs 74%). 4, 2

Additional Androgen Markers (in order of diagnostic utility)

1. Calculated free testosterone (cFT): Highest sensitivity at 89% with 83% specificity—calculate using Vermeulen equation from high-quality TT and SHBG measurements 4, 2

2. Free androgen index (FAI): 78% sensitivity, 85% specificity—use when cFT unavailable, calculated as (TT/SHBG) × 100 4, 2

   • Caveat: Inaccurate if SHBG <30 nmol/L 4

3. Androstenedione (A4): 75% sensitivity, 71% specificity—useful when SHBG is low 4, 2

4. DHEAS: 75% sensitivity, 67% specificity—most reliable for adrenal androgen production, particularly valuable in women <30 years 4, 2

Functional Free Testosterone

• Equilibrium dialysis or ammonium sulfate precipitation are gold standard methods but resource-intensive and rarely practical for routine use 4

Additional Laboratory Tests

• LH and FSH: LH/FSH ratio >2:1 found in only 55% of PCOS patients—do not rely on this ratio for diagnosis due to low sensitivity 5, 6
• 17α-hydroxyprogesterone: Screen for non-classic congenital adrenal hyperplasia 1, 7
• TSH and prolactin: Exclude thyroid disease and hyperprolactinemia 1

Ultrasound Assessment

Adults (≥18 years)

Transvaginal ultrasound with ≥8 MHz transducer frequency is the optimal imaging approach. 4, 1

Follicle number per ovary (FNPO) ≥20 follicles is the gold standard ultrasonographic marker, with 87.64% sensitivity and 93.74% specificity. 4, 1

Alternative Ultrasound Markers (when accurate follicle counting impossible)

• Ovarian volume (OV) >10 mL: Use when follicles cannot be accurately counted 4, 1
• Follicle number per single cross-section (FNPS): Secondary alternative marker 4

Adolescents (<20 years, ≥1 year post-menarche)

Avoid ultrasound as primary diagnostic tool in adolescents due to high false-positive rate. Instead, require all three Rotterdam criteria with emphasis on clinical/biochemical hyperandrogenism plus menstrual irregularity persisting ≥2 years post-menarche. 1, 3

Metabolic Screening

Screen all women with PCOS for type 2 diabetes and glucose intolerance using fasting glucose and/or oral glucose tolerance test. 1, 3

Obtain fasting lipid panel to screen for dyslipidemia. 1

Differential Diagnosis to Exclude

• Cushing's syndrome 1
• Androgen-secreting tumors (ovarian or adrenal)—suspect with rapid onset, severe hyperandrogenism 1, 3
• Non-classic congenital adrenal hyperplasia 1
• Thyroid disease 1
• Hyperprolactinemia 1
• Primary ovarian failure 1
• Acromegaly 1

Common Pitfalls

• Do not use LH/FSH ratio as diagnostic criterion—only 35-44% of PCOS patients have elevated ratios 5
• Avoid direct immunoassays for testosterone—they have significantly lower accuracy than LC-MS/MS 4, 2
• Do not diagnose PCOS in adolescents <2 years post-menarche—menstrual irregularity is physiologic in this period 3
• Ensure SHBG >30 nmol/L when using FAI—below this threshold, FAI becomes unreliable 4