What is the management approach for a patient with hematuria (blood in urine) following blunt trauma to the lumbar region?

Management of Hematuria Following Blunt Lumbar Trauma

In hemodynamically stable patients with blunt lumbar trauma and gross hematuria OR microhematuria with hypotension, perform contrast-enhanced CT scan with delayed urographic phase immediately to evaluate for renal injury. 1

Initial Assessment and Hemodynamic Status

The diagnostic approach is fundamentally determined by hemodynamic stability:

• Hemodynamically stable patients: Proceed directly to contrast-enhanced CT with delayed urographic phase as the gold standard imaging modality 1
• Hemodynamically unstable patients: E-FAST (Extended Focused Assessment with Sonography for Trauma) can rapidly detect free intra-abdominal fluid, though it has low sensitivity and specificity for kidney trauma specifically 1
• Patients with persistent instability and positive FAST: Proceed to urgent surgery if they cannot be stabilized with fluid resuscitation 1

Indications for Imaging in Blunt Trauma

The presence and degree of hematuria guides imaging decisions, but hematuria alone does not predict injury severity. 1

Adults - Mandatory CT Imaging Criteria:

• Gross (macroscopic) hematuria - any amount 1
• Microhematuria with hypotension (systolic BP <90 mmHg) 1
• High-energy deceleration trauma regardless of hematuria presence 1
• Flank ecchymosis, rib fractures, or flank hematoma 1, 2

Critical Caveat:

10-25% of high-grade kidney injuries and 24-50% of ureteropelvic junction injuries present WITHOUT hematuria. 1 Therefore, mechanism of injury and physical findings are equally important as hematuria in determining imaging needs.

Microhematuria Without Hypotension:

Multiple prospective studies demonstrate that isolated microhematuria (<50 RBC/HPF) in normotensive patients with blunt trauma rarely indicates significant injury requiring intervention 3, 4, 5. However, imaging should still be performed if there are associated high-risk features (deceleration mechanism, flank findings, significant associated injuries) 1, 5.

Pediatric Considerations

Children require modified criteria due to anatomical differences (less perirenal fat, thinner abdominal muscles, larger relative kidney size): 1

• Image if >50 RBCs/HPF 1
• Image if any degree of hematuria PLUS: high-energy mechanism, deceleration injury, hypotension, flank hematoma/ecchymosis, rib fractures, or drop in hematocrit 1
• For minimal symptoms with <50 RBCs/HPF: Ultrasound, contrast-enhanced ultrasound, or Doppler with clinical monitoring may suffice for initial evaluation 1

Imaging Protocol

Contrast-enhanced CT scan with delayed urographic phase (10-15 minutes post-contrast) is the gold standard. 1

This protocol is essential because:

• Detects parenchymal injury, vascular injury, and collecting system disruption 1
• Delayed phase identifies urinary extravasation that may be missed on initial imaging (occurs in 0.2% of all cases and 1% of high-grade injuries) 1
• Allows grading using the AAST (American Association for Surgery of Trauma) renal injury scale 1

Alternative Imaging:

• Ultrasound/CEUS: Not recommended for initial adult evaluation in high-energy trauma, but acceptable in pregnant women and pediatric patients 1
• Intravenous urography: Only useful in unstable patients during surgery when CT unavailable 1

Associated Injuries to Evaluate

Bladder injury occurs in 6-8% of patients with pelvic fractures. 1

• If pelvic fracture present: Add retrograde cystography (CT or conventional) to evaluate for bladder rupture 1
• Gross hematuria with pelvic fracture: 30% have bladder injury 1
• Ureteral injury: Rare (<1%) but should be suspected in high-energy deceleration trauma; delayed urographic phase CT is diagnostic 1

Management Based on Injury Grade

Up to 90% of renal injuries are minor (AAST Grade I-II) and managed non-operatively. 1

Non-Operative Management (Majority of Cases):

• Grade I-II injuries: Observation with clinical monitoring; no routine follow-up imaging needed 1
• Grade III injuries: Observation unless clinical deterioration; follow-up imaging only if patient worsens 1
• Grade IV-V injuries: Non-operative management possible in stable patients; repeat CT with delayed phase within 48 hours recommended 1

Indications for Intervention:

• Hemodynamic instability despite resuscitation 1
• Active bleeding on CT: Consider angioembolization rather than surgery 1, 2
• Expanding retroperitoneal hematoma at exploration 1
• Urinary extravasation with complications (urinoma, infection) 2

Common Pitfalls to Avoid

1. Do not rely solely on hematuria presence or degree - 10-25% of high-grade injuries have no hematuria 1
2. Do not skip delayed urographic phase - collecting system injuries may be missed 1
3. Do not perform routine imaging for isolated microhematuria in normotensive adults without high-risk features - this eliminates 75% of unnecessary studies 3
4. Do not rush to surgery - most renal injuries (even high-grade) are managed non-operatively; surgical exploration often leads to nephrectomy 1
5. In children, do not use adult hematuria thresholds - use >50 RBC/HPF as cutoff and consider mechanism/clinical findings 1