What is the Meares-Stamey 4-glass test?

The Meares-Stamey 4-Glass Test for Diagnosing Prostatitis

The Meares-Stamey 4-glass test is the gold standard diagnostic test for chronic bacterial prostatitis that involves collecting four sequential specimens: first-void urine, midstream urine, expressed prostatic secretions (EPS), and post-massage urine to localize infection to the prostate. 1, 2

Components and Collection Process

• The test consists of collecting four sequential specimens 1, 2:

  1. First-void urine (VB1) - represents urethral flora
  2. Midstream urine (VB2) - represents bladder urine
  3. Expressed prostatic secretions (EPS) - obtained through prostatic massage
  4. Post-massage urine (VB3) - contains prostatic secretions flushed into the urethra

• Proper specimen collection is essential to avoid contamination and ensure accurate results 3

• The test is considered positive if there is a 10-fold higher bacterial count in the EPS than in the midstream urine sample 1, 2

Clinical Utility and Interpretation

• The primary purpose is to differentiate between urethral, bladder, and prostatic infections by localizing the source of inflammation and infection 2, 3

• Gram stain or cell counts are performed on specimens to identify inflammatory cells, and aerobic culture to identify pathogens 2

• Common pathogens identified in chronic bacterial prostatitis include Escherichia coli, other enteric bacteria, Pseudomonas species, Staphylococcus aureus, and Enterococcus 1

• Chronic pelvic pain syndrome (Category III prostatitis) is not frequently caused by culturable infectious agents, making the test valuable for distinguishing between bacterial and non-bacterial forms 1, 3

Simplified Variants

• A 2-glass test variant involves only collecting midstream urine and EPS specimens, which is more practical for office settings 1, 2

• The 2-glass pre-massage and post-massage test (PPMT) has shown strong concordance with the 4-glass test, with studies showing it predicts correct diagnosis in more than 96% of subjects 4

• A 3-glass test (pre-ejaculation, ejaculation, and post-ejaculation) has been proposed as an alternative when prostatic secretions cannot be obtained through massage 5

Clinical Challenges and Considerations

• Despite being the gold standard, the 4-glass test is not widely used in clinical practice due to:

  • Time-consuming procedure 4
  • Technical complexity 6
  • Patient discomfort 6
  • Additional expense 4

• Expressed prostatic secretions are successfully recovered in less than 50% of examined patients, which can result in non-diagnostic tests 5

• The test should not be performed in cases of suspected acute bacterial prostatitis due to the risk of bacteremia from prostatic massage 2

• The test is particularly valuable for antimicrobial stewardship by ensuring targeted antibiotic therapy rather than empiric treatment 6, 7

Diagnostic Accuracy

• The 4-glass test remains the most specific method for identifying bacterial infections localized within the prostate 6

• For chronic bacterial prostatitis, a minimum 4-week course of antibiotics (up to 12 weeks) may be required based on test results 7

• Fluoroquinolones remain first-line therapy when susceptible organisms are identified, followed by trimethoprim-sulfamethoxazole or doxycycline 7

The Meares-Stamey 4-glass test continues to be the reference standard for diagnosing prostatitis, particularly for differentiating between bacterial and non-bacterial forms, though simplified variants may be appropriate in many clinical settings due to practical considerations.