Management of Visible Blood in Urine with 0 RBCs on Urinalysis
This finding represents a false-positive dipstick result that does not meet the diagnostic threshold for true hematuria, and no urologic workup is indicated at this time. 1
Understanding the Diagnostic Threshold
The critical distinction here is that true hematuria requires ≥3 red blood cells per high-power field (RBC/HPF) on microscopic examination, not just a positive dipstick test. 1, 2, 3
- A urinalysis showing 0 RBCs falls within the normal range (0-2 RBCs/HPF is considered normal). 1
- The American Urological Association explicitly states that "a dipstick reading suggestive of hematuria should not lead to imaging or further investigation without confirmation of three or greater red blood cells per high power field." 1
- Dipstick tests have limited specificity (65-99%) and frequently produce false-positive results. 1, 2
What Causes False-Positive Dipstick Results?
The dipstick detects heme pigment, not intact red blood cells, which explains why you can see "blood" on the dipstick but 0 RBCs on microscopy. 4
Common causes of false-positive dipstick results include:
- Myoglobinuria from rhabdomyolysis (though this is typically associated with elevated creatine phosphokinase). 4
- Hemoglobinuria from intravascular hemolysis. 4
- Contamination with menstrual blood in female patients. 1, 2
- Concentrated urine causing false readings. 1
- Certain medications or foods that color the urine. 1
Recommended Management Approach
Document this finding as within normal limits and do not proceed with urologic evaluation. 1
- No cystoscopy is indicated. 1
- No CT urography is indicated. 1
- No urology referral is needed. 1
- Simply document the discrepancy between dipstick and microscopy. 1
Critical Caveats: When to Reconsider
You should obtain a repeat urinalysis with microscopy if any of the following develop:
- New urologic symptoms such as irritative voiding symptoms (urgency, frequency), flank pain, or dysuria. 1, 2
- Visible gross hematuria that the patient can actually see. 1, 2
- Systemic symptoms suggesting rhabdomyolysis (muscle pain, weakness, dark urine with elevated CPK). 4
If a subsequent urinalysis shows ≥3 RBCs/HPF on microscopic examination, then full urologic evaluation would be warranted, particularly in a male patient who may have additional risk factors such as age >40 years, smoking history, or occupational chemical exposure. 1, 2, 3
Common Pitfall to Avoid
Never initiate a full hematuria workup based solely on dipstick positivity without microscopic confirmation. 1, 2 This is a frequent error that leads to unnecessary invasive testing (cystoscopy), radiation exposure (CT urography), and patient anxiety. 5 The American Academy of Family Physicians emphasizes that confirmation with microscopic urinalysis showing ≥3 RBCs/HPF on at least two of three properly collected specimens is required before any workup begins. 1, 2