What is the recommended approach for evaluating hematuria (blood in the urine)?

Recommended Approach for Evaluating Hematuria

The evaluation of hematuria requires a risk-stratified approach with CT urography as the preferred imaging modality for adults, while ultrasound is the initial imaging of choice for children. 1

Definition and Initial Confirmation

• Microscopic hematuria: ≥3 red blood cells per high-power field on microscopic evaluation from two of three properly collected specimens 1
• Gross (macroscopic) hematuria: Blood in urine visible to the naked eye
• Important: Always confirm dipstick positivity with microscopic examination due to limited specificity (65-99%) 1

Risk Assessment

The American Urological Association defines three risk categories for patients with hematuria:

• Low risk (0-0.4% malignancy risk)
• Intermediate risk (0.2-3.1% malignancy risk)
• High risk (1.3-6.3% malignancy risk) 1

Key Risk Factors for Urinary Malignancy

• Age >60 years
• Male gender
• Smoking history
• Exposure to industrial chemicals
• Family history of renal cancer
• History of pelvic radiation 1

Diagnostic Algorithm

Step 1: Laboratory Evaluation

• Complete blood count
• Serum creatinine and BUN
• Urinalysis with microscopic examination
• Urine culture if infection is suspected 1
• Assess for dysmorphic RBCs, cellular casts, or proteinuria (suggests renal parenchymal disease) 1

Step 2: Imaging Selection

For adults:

• CT Urography: Preferred first-line imaging (sensitivity 92%, specificity 93%) 1
• MR Urography: Alternative for patients with contrast allergy or renal insufficiency 1
• Renal Ultrasound: Alternative or for younger patients (sensitivity 50%, specificity 95%) 1

For children:

• Ultrasound: First-line imaging for pediatric hematuria evaluation 2
• CT: Reserved for specific indications in children such as trauma 2

Step 3: Advanced Evaluation

• Cystoscopy: Required for evaluation of both upper and lower urinary tracts 1

  • Mandatory for patients with:
    • Gross hematuria (immediate referral recommended)
    • Age >60 years with unexplained hematuria
    • Persistent hematuria after treatment
    • Recurrent UTIs 1

• Retrograde cystography: Mandatory for patients with gross hematuria and pelvic fracture (minimum 300mL contrast) 1

Special Considerations

Anticoagulation Therapy

• Patients on antiplatelet or anticoagulant therapy should still be referred for urologic evaluation
• Anticoagulation is not an adequate explanation for hematuria and rarely causes abnormal findings without underlying pathology 1

Glomerular vs. Non-glomerular Hematuria

• Presence of dysmorphic RBCs, cellular casts, or proteinuria suggests glomerular origin
• The combination of proteinuria and hematuria strongly predicts parenchymal renal disease 1
• Patients with isolated glomerular hematuria require follow-up at six-month intervals 3

Follow-up Recommendations

• Low-risk patients: Annual urinalysis 1
• Intermediate/high-risk patients: Urine cytology and repeat urinalysis at 6,12,24, and 36 months 1
• After UTI treatment: Repeat urinalysis 1-2 weeks after completing antibiotics 1
• High-risk patients with history of gross hematuria: Surveillance with repeat imaging and cystoscopy 1

Common Pitfalls to Avoid

1. Relying solely on dipstick testing without microscopic confirmation 1
2. Failing to repeat urinalysis after treating a presumed cause 1
3. Relying solely on ultrasound for trauma patients with gross hematuria 1
4. Using inadequate contrast volume for cystography (minimum 300mL needed) 1
5. Collecting urine samples from extension tubing or collection bag instead of after changing catheter 1
6. Assuming anticoagulation therapy is the cause of hematuria without proper evaluation 1