What is the recommended imaging protocol for patients presenting with hematuria (blood in urine)?

Imaging Protocol for Hematuria Evaluation

CT urography (CTU) without and with IV contrast is the recommended first-line imaging test for patients with gross hematuria or microhematuria with risk factors, due to its superior diagnostic accuracy for detecting urinary tract abnormalities. 1

Adult Patients

Gross Hematuria

• CTU without and with IV contrast is the imaging modality of choice for initial evaluation of gross hematuria, with pooled sensitivity of 96% and specificity of 99% for detecting urothelial malignancy 1, 2
• MRU without and with IV contrast is an appropriate alternative when CT is contraindicated 1
• Conventional radiographs (KUB) and intravenous urography (IVU) are no longer recommended as first-line imaging for hematuria evaluation 1

Microhematuria

• For patients with risk factors: CTU without and with IV contrast is recommended 1
• For patients without risk factors or with identified benign causes: CT abdomen and pelvis without IV contrast may be appropriate 1
• Risk factors include: age >35 years, history of smoking, occupational exposure to chemicals or dyes, history of gross hematuria, irritative voiding symptoms, or prior urologic disease 2
• Ultrasound has lower sensitivity compared to CTU and is not recommended as first-line imaging for microhematuria with risk factors 1, 3

Special Populations

• Pregnant patients: Ultrasound of kidneys and bladder is the recommended initial imaging test 1, 2
• Patients with contraindications to iodinated contrast: MRU without and with IV contrast is appropriate 1

Pediatric Patients

• Nonpainful, nontraumatic isolated microscopic hematuria without proteinuria: Imaging is usually not appropriate 1
• Nonpainful, nontraumatic isolated microscopic hematuria with proteinuria: Ultrasound of kidneys and bladder is recommended 1
• Nonpainful, nontraumatic isolated macroscopic hematuria: Ultrasound of kidneys and bladder is recommended 1
• Painful, nontraumatic hematuria with suspected urolithiasis: Either ultrasound of kidneys and bladder or CT abdomen and pelvis without IV contrast is appropriate 1
• Traumatic macroscopic hematuria: CT abdomen and pelvis with IV contrast is recommended 1
• Traumatic microscopic hematuria: CT abdomen and pelvis with IV contrast is appropriate in specific scenarios (congenital renal abnormalities, multiorgan injury, deceleration injury, flank pain/ecchymosis) 1

Technical Considerations for CT Urography

• CTU protocol should include both precontrast and excretory phases to optimize detection of urinary tract abnormalities 1, 4
• The excretory phase is essential for evaluation of the collecting systems, ureters, and bladder 4, 3
• CTU has demonstrated superior diagnostic accuracy compared to IVU with an accuracy of 99.6% versus 84.9% 1, 4
• CTU can detect both nephrogenic and urogenic causes of hematuria in a single examination 1, 3

Clinical Pitfalls and Considerations

• Ultrasound has limited sensitivity for detecting urothelial lesions, with sensitivity ranging from 35.3-50.7% compared to cystoscopy 1, 2
• In cases of suspected urethral injury (blood at urethral meatus, pelvic fractures), retrograde urethrography should be performed before bladder catheter placement 1, 2
• For suspected bladder injury with pelvic fractures, CT cystography (CT after retrograde bladder filling with contrast) is recommended 1
• In young adults (<40 years) with microhematuria and no risk factors, unenhanced CT may be sufficient as most significant findings (94.8%) are evident on unenhanced images 5, 6
• Cystoscopy remains essential for complete evaluation of hematuria, as bladder cancer is the most common malignancy detected in patients with hematuria 2, 4

Diagnostic Yield

• Clinically significant findings are detected in approximately 22.1% of CT urograms in young adults with hematuria 5
• Findings are more frequent in patients with visible (gross) hematuria (48%) than in patients with non-visible (microscopic) hematuria (29%) 6
• The most common significant findings are urinary tract calculi (75.3% of significant findings) 5, 6
• Malignancies are rare in young adults but increase in frequency with age and risk factors 5, 7