Evaluation of Prostatitis
The evaluation of prostatitis requires a focused history, gentle digital rectal examination (avoiding vigorous prostatic massage in acute cases), urinalysis with culture, and the Meares-Stamey 4-glass test (or 2-specimen variant) for chronic bacterial prostatitis, with a positive result defined as a 10-fold higher bacterial count in expressed prostatic secretions compared to midstream urine. 1, 2
Initial Clinical Assessment
History Taking
Obtain a detailed medical history focusing on:
- Duration and nature of urinary symptoms (dysuria, frequency, urgency, retention) 1, 3
- Pelvic pain characteristics including location, severity, and radiation 1, 4
- Ejaculatory pain or discomfort 1
- Fever, chills, or systemic symptoms suggesting acute bacterial prostatitis 4, 5
- Previous urinary tract infections or recurrent UTIs indicating possible chronic bacterial prostatitis 4, 6
- Recent urologic procedures (catheterization, cystoscopy, prostate biopsy) as risk factors 5
- Sexual history to assess for sexually transmitted infections 3
Validated Symptom Questionnaires
Use the NIH Chronic Prostatitis Symptom Index (NIH-CPSI) to quantify symptom severity (scale 0-43), with a 6-point change considered clinically meaningful 4. Alternative validated tools include the I-PSS with bother score, DAN-PSS, or ICIQ-MLUTS 7.
Physical Examination
Key Examination Components
- Assess suprapubic area for bladder distention 7, 3
- Examine external genitalia for abnormalities 3
- Perform digital rectal examination to evaluate:
Critical Safety Consideration
Avoid vigorous prostatic massage or aggressive digital rectal examination in suspected acute bacterial prostatitis due to risk of bacteremia 1, 2, 5. A gentle DRE is acceptable, but the Meares-Stamey test should not be performed in acute cases 1, 2.
Laboratory Evaluation
Essential Tests for All Patients
Urinalysis with dipstick testing to identify:
- Pyuria (white blood cells) 7, 1
- Hematuria 7, 1
- Proteinuria 7, 1
- Positive nitrite test suggesting bacterial infection 7
Midstream urine culture is mandatory to:
- Identify causative organisms in acute bacterial prostatitis 2, 5
- Guide antibiotic selection based on sensitivity patterns 3, 5
- Distinguish bacterial from non-bacterial prostatitis 6, 8
Blood cultures should be obtained in febrile patients with suspected acute bacterial prostatitis 2.
Complete blood count to assess for leukocytosis in acute cases 2.
Gold Standard for Chronic Bacterial Prostatitis
The Meares-Stamey 4-glass test is the definitive diagnostic test, involving sequential collection of: 1, 2
- 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) is acceptable and more practical 1, 2.
Positive diagnosis requires:
- 10-fold higher bacterial count in EPS compared to midstream urine 1, 2
- Gram stain or cell counts to identify inflammatory cells 1
- Aerobic culture to identify pathogens 1
Common Bacterial Pathogens
Acute bacterial prostatitis (80-97% gram-negative): 2, 4
- Escherichia coli (most common)
- Klebsiella pneumoniae
- Pseudomonas aeruginosa
- Gram-positive organisms: Staphylococcus aureus, Enterococcus species, Group B streptococci
Chronic bacterial prostatitis (up to 74% gram-negative): 1, 2
- E. coli (predominant)
- Proteus mirabilis
- Enterobacter species
- Serratia marcescens
Additional Diagnostic Studies
When to Consider Imaging
Transrectal ultrasound (TRUS) is indicated to: 1, 2
- Assess prostate volume more accurately than DRE
- Rule out prostatic abscess in selected acute cases with poor response to antibiotics
- Exclude other prostatic pathology
Uroflowmetry helps correlate symptoms with objective voiding dysfunction 1.
For Patients with Storage Symptoms
Bladder diary for at least 3 days is recommended for patients with: 1
- Predominant nocturia
- Urinary frequency
- To identify nocturnal polyuria or excessive fluid intake
Frequency-volume charts help distinguish between true bladder pathology and behavioral factors 7.
Differential Diagnosis Considerations
Exclude other conditions that may mimic prostatitis: 2, 3
- Acute epididymitis (epididymal rather than prostatic tenderness)
- Benign prostatic hyperplasia
- Urinary tract stones
- Bladder cancer
- Urethritis from sexually transmitted infections (especially in men <35 years)
Testing for Atypical Pathogens
In chronic prostatitis/chronic pelvic pain syndrome, test for: 2
- Chlamydia trachomatis
- Mycoplasma species These require specific antimicrobial therapy if identified.
Classification-Specific Evaluation
Acute Bacterial Prostatitis
- Diagnosis primarily clinical based on history and physical examination 5, 6
- Midstream urine culture sufficient for pathogen identification 2, 5
- Do not perform Meares-Stamey test 1, 2
Chronic Bacterial Prostatitis
- Requires Meares-Stamey test for definitive diagnosis 1, 2, 9
- Often presents as recurrent UTIs from the same bacterial strain 4, 6
- Minimum 4-week antibiotic course needed (levofloxacin or ciprofloxacin) 10, 4
Chronic Prostatitis/Chronic Pelvic Pain Syndrome (CP/CPPS)
- Diagnosis of exclusion when bacterial cultures are negative 1, 4
- Pelvic pain or discomfort for ≥3 months with urinary symptoms 4
- Not frequently caused by culturable infectious agents 1, 2
- Requires different management focused on symptom relief rather than antimicrobials 2
Common Pitfalls to Avoid
- Never perform vigorous prostatic massage in acute prostatitis due to bacteremia risk 1, 2, 5
- Do not start antibiotics immediately without appropriate workup (except in acute febrile cases), as this may obscure diagnosis 9
- Avoid empiric amoxicillin or ampicillin due to very high worldwide resistance rates 2
- Do not stop antibiotics prematurely in bacterial prostatitis, as this can lead to chronic infection 2
- All UTIs in men are considered complicated and require thorough evaluation 3