Expected Urine Microscopy Findings in Bladder Pain Syndrome
The urine microscopy in bladder pain syndrome should be normal, with no evidence of infection, pyuria, or other abnormalities—the absence of pathological findings on urinalysis is a diagnostic requirement for BPS. 1
Key Diagnostic Principle
The diagnosis of BPS fundamentally requires documented negative urine cultures and an unremarkable urinalysis, as the condition is defined by the absence of infection or other identifiable causes that could explain the symptoms. 1, 2
Specific Expected Findings
Normal Urinalysis Components
- No white blood cells (WBCs): Pyuria should be absent, as its presence suggests urinary tract infection or other inflammatory conditions that would exclude BPS. 1
- No bacteria: The microscopy should show no organisms, though urine culture remains mandatory even with negative microscopy to detect lower bacterial counts not visible on dipstick or microscopic examination. 1
- No red blood cells (RBCs): While microhematuria may occasionally be present and warrants evaluation (particularly in smokers), the typical BPS patient has no hematuria on microscopy. 1
- No casts, crystals, or other cellular elements: The sediment should be unremarkable. 1
Critical Diagnostic Considerations
When Abnormalities Are Found
- If pyuria or bacteriuria is present: This excludes the diagnosis of BPS until infection is treated and symptoms persist for at least 6 weeks after documented negative cultures. 1, 2
- If hematuria is present: A complete hematuria workup must be performed, especially in patients with tobacco exposure, to exclude bladder cancer before attributing symptoms to BPS. 1
- If any abnormal cells are seen: Urine cytology should be obtained to rule out malignancy, particularly in smokers or those with environmental exposures. 1, 2
Duration Requirement
- Symptoms must be present for at least 6 weeks with documented negative urine cultures before BPS can be diagnosed—a single normal urinalysis is insufficient. 1, 2
Common Pitfall
The most critical error is diagnosing BPS without adequately excluding urinary tract infection. Even when urinalysis appears normal by dipstick or microscopy, formal urine culture is mandatory because clinically significant lower bacterial counts may not be readily identifiable on microscopic examination alone. 1