What is the diagnostic approach for chronic prostatitis?

Diagnosing Chronic Prostatitis

The diagnosis of chronic prostatitis requires the Meares-Stamey 4-glass test or its 2-specimen variant, with a positive result indicated by a 10-fold higher bacterial count in the expressed prostatic secretions compared to midstream urine. 1, 2

Classification of Prostatitis

• Prostatitis affects approximately 9.3% of men in their lifetime, with fewer than 10% of cases confirmed to have bacterial infection 2
• Four categories of prostatitis exist:
  • Category I: Acute bacterial prostatitis
  • Category II: Chronic bacterial prostatitis
  • Category III: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)
  • Category IV: Asymptomatic inflammatory prostatitis 3, 4

Diagnostic Approach for Chronic Bacterial Prostatitis

Initial Assessment

• Complete medical history focusing on urinary symptoms, pelvic pain, and ejaculatory pain 1
• Use validated symptom score questionnaires to assess severity and quality of life impact 1
• Digital rectal examination to estimate prostate volume (though less accurate than ultrasound) 1

Laboratory Testing

• Urinalysis to identify UTIs, proteinuria, hematuria, or glycosuria 1
• The gold standard diagnostic test is the Meares-Stamey 4-glass test which includes:
  • First-void urine
  • Midstream urine
  • Expressed prostatic secretions (EPS)
  • Post-massage urine 1, 2
• A simplified 2-specimen variant involves only midstream urine and EPS specimens 1, 2
• Gram stain or cell counts of specimens to identify inflammatory cells 1
• Aerobic culture of specimens to identify pathogens 1

Interpretation of Results

• Positive diagnosis requires a 10-fold higher bacterial count in the EPS than the midstream urine 1, 2
• Common pathogens in chronic bacterial prostatitis:
  • Gram-negative organisms (74% of cases): E. coli, Proteus mirabilis, Enterobacter species, Serratia marcescens 2
  • Gram-positive bacteria: Staphylococcus aureus, Enterococcus species, Group B streptococci 2

Additional Testing

• Prostate-specific antigen (PSA) may be elevated in prostatitis and can decrease with treatment 5
• Transrectal ultrasound may be useful to assess prostate volume and rule out other conditions 1
• Uroflowmetry can help correlate symptoms with objective findings 1

Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS)

• CP/CPPS is characterized by pelvic pain for more than 3 months, urinary symptoms, and painful ejaculation without documented urinary tract infections 3
• Diagnosis is primarily based on exclusion of other urologic conditions 6, 4
• CP/CPPS is not frequently caused by a culturable infectious agent 1

Diagnostic Pitfalls and Considerations

• Avoid prostatic massage in suspected acute prostatitis due to risk of bacteremia 2
• Differential diagnosis includes acute cystitis, benign prostatic hyperplasia, urinary tract stones, bladder cancer, prostatic abscess 6
• Chronic prostatitis can elevate PSA levels, potentially leading to unnecessary prostate biopsies 5
• Bladder diary for at least 3 days is recommended for patients with storage symptoms or nocturia 1

Follow-up Testing

• Monitor response to treatment with repeat cultures and symptom assessment 7
• Consider reassessing PSA levels after treatment, as successful therapy can lower elevated PSA values 5

By following this diagnostic algorithm, clinicians can accurately diagnose chronic prostatitis and distinguish between bacterial and non-bacterial forms, leading to appropriate treatment decisions and improved patient outcomes.