What investigations are recommended for the diagnosis of Polycystic Ovary Syndrome (PCOS)?

Recommended Investigations for PCOS Diagnosis

The diagnosis of Polycystic Ovary Syndrome (PCOS) requires specific laboratory tests, including total testosterone, free testosterone, TSH, prolactin, and a two-hour oral glucose tolerance test, along with transvaginal ultrasound assessment of ovarian morphology when appropriate. 1

Essential Laboratory Tests

First-Line Hormonal Assessment

• Androgen Profile:
  • Total testosterone (TT) and free testosterone (FT) using liquid chromatography with tandem mass spectrometry (LC-MS/MS) as the preferred method 1
  • Sex hormone-binding globulin (SHBG) to calculate free androgen index

Exclusion of Other Conditions

• Thyroid-stimulating hormone (TSH) to rule out thyroid disorders 1
• Prolactin to exclude hyperprolactinemia 1
• Two-hour oral glucose tolerance test with 75g glucose load to assess insulin resistance 1
• Fasting lipid profile to evaluate metabolic health 1

Additional Tests When Clinically Indicated

• 17-hydroxyprogesterone (preferably in early morning) to exclude non-classic congenital adrenal hyperplasia
• Screening for Cushing's syndrome if clinical signs are present (e.g., central obesity, striae, moon facies) 1

Ultrasound Assessment

Transvaginal Ultrasound Criteria

• Follicle number per ovary (FNPO) ≥20 follicles (2-9mm) and/or ovarian volume ≥10ml 2, 1
• Transvaginal approach is preferred if sexually active and acceptable to the patient 2
• Using endovaginal ultrasound transducers with frequency bandwidth including 8MHz 2

Important Considerations for Ultrasound

• Ultrasound should NOT be used for diagnosis in those with gynecological age <8 years (less than 8 years after menarche) due to high incidence of multi-follicular ovaries 2
• For transabdominal ultrasound, focus on ovarian volume with threshold of ≥10ml 2
• Ensure no corpora lutea, cysts, or dominant follicles are present during assessment 2

Reporting Standards

• Document last menstrual period, transducer bandwidth frequency, and approach/route 2
• Report total follicle number per ovary (2-9mm), three dimensions and volume of each ovary 2
• Endometrial thickness and appearance should be reported 2

Role of Anti-Müllerian Hormone (AMH)

• Serum AMH should NOT yet be used as an alternative for detecting polycystic ovarian morphology or as a single test for PCOS diagnosis 2
• While AMH levels are significantly higher in women with PCOS, there are challenges in standardization of assays and determining appropriate cut-offs 2

Diagnostic Approach Algorithm

1. Clinical Assessment:

   • Evaluate for oligo/anovulation (irregular menstrual cycles)
   • Assess for clinical hyperandrogenism (hirsutism, acne, male-pattern hair loss)

2. Laboratory Testing:

   • Perform androgen profile (total testosterone, free testosterone)
   • Complete exclusionary tests (TSH, prolactin)
   • Assess metabolic parameters (glucose tolerance test, lipid profile)

3. Imaging:

   • Perform transvaginal ultrasound if:
     • Patient is ≥8 years post-menarche
     • Patient has irregular cycles but no hyperandrogenism
     • Additional diagnostic clarity is needed

4. Diagnosis Confirmation:

   • Apply Rotterdam criteria (requires 2 of 3):
     • Oligo/anovulation
     • Clinical and/or biochemical hyperandrogenism
     • Polycystic ovaries on ultrasound

Important Caveats

• Ultrasound technology is rapidly evolving, requiring regular revision of PCOM thresholds 2
• FNPO has the highest diagnostic accuracy (sensitivity 84%, specificity 91%) compared to ovarian volume (sensitivity 81%, specificity 81%) 1
• In patients with irregular menstrual cycles and hyperandrogenism, ovarian ultrasound is not necessary for PCOS diagnosis 2
• MRI of the pelvis without contrast can be an alternative for evaluating ovarian morphology when ultrasound is not feasible 1

By following this comprehensive diagnostic approach, clinicians can accurately diagnose PCOS while excluding other conditions that may present with similar symptoms.