What are the clinical steps to diagnose prostatitis?

Clinical Diagnosis of Prostatitis

The diagnosis of prostatitis depends on the clinical subtype: acute bacterial prostatitis is diagnosed primarily through clinical presentation and midstream urine culture, while chronic bacterial prostatitis requires the Meares-Stamey 4-glass test (or 2-specimen variant) demonstrating a 10-fold higher bacterial count in expressed prostatic secretions compared to midstream urine. 1

Initial Clinical Assessment

History and Symptom Evaluation

• Obtain a focused history on urinary symptoms (frequency, urgency, dysuria), pelvic pain (perineal, suprapubic, rectal), and ejaculatory pain or discomfort 1
• Use the NIH Chronic Prostatitis Symptom Index (NIH-CPSI) to quantify symptom severity, with a 6-point change considered clinically meaningful 1
• Assess for fever, chills, and systemic symptoms that suggest acute bacterial prostatitis versus chronic presentations 2

Physical Examination

• Examine the suprapubic area for bladder distention 1
• Inspect external genitalia for abnormalities 1
• Perform digital rectal examination to assess prostate size, consistency, shape, symmetry, and anal sphincter tone 1
• In acute bacterial prostatitis, perform DRE gently and avoid vigorous prostatic massage due to risk of bacteremia 3

Laboratory Evaluation

Urinalysis and Culture

• Perform urinalysis with dipstick testing to identify pyuria, hematuria, proteinuria, and positive nitrite test suggesting bacterial infection 1
• Obtain midstream urine culture to identify causative organisms in acute bacterial prostatitis 3
• Collect blood cultures in febrile patients to assess for bacteremia 3

Meares-Stamey Test for Chronic Bacterial Prostatitis

The Meares-Stamey 4-glass test is the gold standard for diagnosing chronic bacterial prostatitis, requiring collection of: 1

• First-void urine (VB1)
• Midstream urine (VB2)
• Expressed prostatic secretions (EPS) after prostatic massage
• Post-massage urine (VB3)

A simplified 2-specimen variant (midstream urine and EPS only) can be used as an alternative 1

Positive diagnosis requires a 10-fold higher bacterial count in the EPS compared to midstream urine 1, 3

Perform Gram stain or cell counts to identify inflammatory cells and aerobic culture to identify pathogens 1

Common Pathogens

• Gram-negative organisms cause 80-97% of acute bacterial prostatitis, including E. coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa 3
• Up to 74% of chronic bacterial prostatitis cases are due to gram-negative organisms, particularly E. coli, Proteus mirabilis, Enterobacter species, and Serratia marcescens 1, 3
• Gram-positive bacteria such as Staphylococcus aureus, Enterococcus species, and Group B streptococci can also cause acute bacterial prostatitis 3

Additional Diagnostic Studies

Imaging and Functional Testing

• Transrectal ultrasound may be useful to assess prostate volume, rule out prostatic abscess in acute cases, and exclude other conditions 1, 3
• Uroflowmetry can help correlate symptoms with objective findings 1
• Complete blood count to assess for leukocytosis in acute bacterial prostatitis 3

Symptom Documentation

• Maintain a bladder diary for at least 3 days for patients with storage symptoms, nocturia, or to identify nocturnal polyuria versus excessive fluid intake 1
• Frequency-volume charts help distinguish true bladder pathology from behavioral factors 1

Differential Diagnosis Considerations

The differential diagnosis includes: 4

• Acute cystitis
• Benign prostatic hyperplasia
• Urinary tract stones
• Bladder cancer
• Prostatic abscess
• Acute epididymitis (epididymal tenderness rather than prostate tenderness) 3
• Enterovesical fistula
• Foreign body within the urinary tract

Classification-Specific Diagnostic Approach

Acute Bacterial Prostatitis

• Diagnosis is primarily clinical with fever, chills, dysuria, and tender prostate on gentle DRE 2
• Midstream urine culture identifies the causative organism 3
• Avoid prostatic massage due to bacteremia risk 3

Chronic Bacterial Prostatitis

• Requires Meares-Stamey test with 10-fold higher bacterial count in EPS versus midstream urine 1
• Fewer than 10% of prostatitis cases are confirmed bacterial infections 1

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

• This is a diagnosis of exclusion when bacterial cultures are negative 3, 2
• Not frequently caused by a culturable infectious agent 1
• Consider testing for atypical pathogens including Chlamydia trachomatis and Mycoplasma species 3

Asymptomatic Prostatitis

• Incidental finding during evaluation for other urologic problems 4, 2
• Does not require treatment 2

Critical Pitfalls to Avoid

• Never perform vigorous prostatic massage in suspected acute prostatitis due to risk of bacteremia 1, 3
• Do not confuse screening PSA guidelines with diagnostic evaluation in symptomatic men presenting with urinary symptoms 5
• Recognize that CP/CPPS requires different management focused on symptom relief rather than antimicrobials 3
• Ensure adequate follow-up as relapse or recurrence of bacterial prostatitis is frequent 6