What are the concerns with a urinalysis (UA) showing a slight trace of blood 12 days after abdominal trauma with otherwise normal results?

Evaluation of Trace Blood in Urinalysis After Abdominal Trauma

A trace amount of blood in the urine 12 days after abdominal trauma with otherwise normal urinalysis results is likely benign, but warrants monitoring for potential delayed complications of renal or urinary tract injury.

Assessment of Hematuria Following Trauma

Hematuria (blood in urine) following abdominal trauma can indicate injury to the kidneys or urinary tract. The significance depends on several factors:

Severity Assessment

• Trace hematuria: Generally less concerning than gross hematuria (visible blood)
• Timing: 12 days post-injury suggests either:
  • Resolution of a minor injury
  • Delayed manifestation of a complication

Key Considerations

1. Degree of hematuria

   • Trace blood on dipstick with normal urinalysis is less concerning than gross hematuria
   • According to guidelines, microscopic hematuria alone is a poor predictor of significant genitourinary tract damage 1

2. Mechanism of original injury

   • High-energy trauma (falls from height, motor vehicle accidents) carries higher risk
   • Direct blow to the flank area increases kidney injury risk

3. Associated symptoms

   • Pain in flank or abdomen
   • Fever
   • Decreased urine output
   • Abdominal distention

Potential Concerns

Delayed Complications

• Urinoma formation: Collection of urine that has leaked from the collecting system
• Delayed bleeding: Particularly with pseudoaneurysm formation
• Infection: Secondary infection of injured tissue
• Scarring: May lead to long-term issues like hypertension

When to Seek Immediate Medical Attention

• Development of flank pain
• Fever
• Increasing hematuria (especially gross blood)
• Abdominal distention or increasing pain
• Decreased urine output

Follow-up Recommendations

The Kidney and Uro-Trauma Guidelines recommend 1:

• For minor injuries: Follow-up imaging is not required for minor (AAST I-II) renal injuries managed non-operatively
• For moderate/severe injuries: Follow-up imaging is driven by clinical condition
• Return to activities: Return to sport activities should be allowed only after microscopic hematuria is resolved

Monitoring Plan

1. Repeat urinalysis:

   • Consider repeat testing in 1-2 weeks to confirm resolution
   • The American Urological Association recommends yearly urinalyses after initial negative workup for asymptomatic microhematuria 2

2. Follow-up evaluation:

   • If hematuria persists beyond 4 weeks or worsens, further evaluation may be needed
   • If two consecutive annual urinalyses are negative, no further evaluation is necessary 2

3. Blood pressure monitoring:

   • Consider periodic monitoring of blood pressure for up to a year after injury to detect renovascular hypertension 1

When Further Imaging Is Warranted

Consider further imaging if:

• Hematuria persists or worsens
• New symptoms develop (pain, fever, decreased urine output)
• Original injury was high-energy or directly to the flank
• Other concerning clinical findings develop

Conclusion

While trace blood in the urine 12 days after abdominal trauma with otherwise normal results is likely benign, monitoring for resolution is important. If symptoms develop or hematuria persists, further evaluation with appropriate imaging should be considered to rule out delayed complications of urinary tract injury.