What is the recommended initial imaging test for a patient presenting with hematuria and back pain?

Imaging for Hematuria with Back Pain

CT urography (CTU) without and with IV contrast is the recommended initial imaging test for patients presenting with hematuria and back pain due to its superior ability to detect both renal parenchymal and urothelial lesions. 1

Rationale for CT Urography

• CTU provides comprehensive evaluation of the entire urinary tract with excellent sensitivity (96%) and specificity (99%) for detecting urothelial malignancy 1
• Superior detection of upper tract tumors, renal parenchymal abnormalities, and urinary calculi in a single examination 2
• Can effectively diagnose multiple potential causes of hematuria with back pain including:
  • Urolithiasis (kidney stones)
  • Renal or urothelial malignancies
  • Renal parenchymal disease
  • Vascular abnormalities like Page kidney 3
  • Structural issues such as nephroptosis 4

Patient-Specific Considerations

Age-Based Approach

• Patients >35 years or with risk factors: CTU without and with IV contrast is strongly recommended 2, 1
• Patients <50 years without risk factors: CT abdomen and pelvis without IV contrast may be sufficient 2
• Children:
  • With nontraumatic microscopic hematuria without proteinuria: Usually no imaging needed
  • With proteinuria or macroscopic hematuria: Ultrasound of kidneys and bladder 2

Special Populations

• Pregnant patients: Ultrasound of kidneys and bladder is recommended to avoid radiation exposure 2, 1
• Renal insufficiency or contrast allergy: MR urography (MRU) without and with IV contrast is an appropriate alternative 2, 1

Protocol Details

• CTU should include:
  • Unenhanced phase (for calculi detection)
  • Nephrographic phase (for renal parenchymal evaluation)
  • Excretory phase (for urothelial assessment) 1
• This multi-phase approach allows for optimal detection of various pathologies that can cause hematuria with back pain 5

Common Pitfalls to Avoid

• Don't rely solely on ultrasound in non-pregnant adults: Limited sensitivity (35.3-50.7%) compared to CT for detecting significant urinary tract pathology 2, 6
• Don't assume kidney stones are the only cause: Patients with flank pain and hematuria may have other serious conditions like Page kidney or malignancy 3
• Don't miss positional conditions: Some causes of hematuria with back pain (like nephroptosis) may require imaging in both supine and upright positions 4
• Don't underestimate microscopic hematuria: Even microscopic hematuria can indicate serious pathology, particularly in patients with risk factors 6

Risk Stratification

• Higher risk for malignancy:
  • Age >35 years
  • Smoking history
  • Occupational exposures
  • Prior urologic disease
  • Gross hematuria (10% have urinary tract tumors) 1, 6
• Lower risk:
  • Age <40 years without risk factors
  • Microscopic hematuria with <5 RBCs/HPF on repeated urinalysis 6

In conclusion, while the diagnostic approach may vary based on patient characteristics, CTU without and with IV contrast remains the gold standard initial imaging test for evaluating hematuria with back pain in most adult patients due to its comprehensive evaluation capabilities and high diagnostic accuracy.