Should a CT scan trauma workup be performed with or without contrast?

CT Scan Trauma Workup Should Be Performed With IV Contrast

For trauma workup, CT scans should be performed with intravenous (IV) contrast rather than without contrast to maximize detection of injuries and active bleeding.

Rationale for Using IV Contrast in Trauma CT

Benefits of Contrast-Enhanced CT

• Improved visualization of vascular injuries: IV contrast allows detection of active hemorrhage, which appears as extravasated contrast material with higher attenuation values (85-370 HU, mean 132 HU) compared to clotted blood (40-70 HU, mean 51 HU) 1
• Better identification of solid organ injuries: Contrast enhancement significantly improves detection of injuries to liver, spleen, and kidneys 2
• Evaluation of mediastinal structures: Contrast-enhanced chest CT is an effective screening tool for determining wound trajectory and likelihood of injury to mediastinal structures 2
• Detection of active bleeding sources: Contrast helps differentiate between arterial and venous hemorrhage, which may have different treatment implications 2

Specific Trauma Applications

• Abdominal trauma: CT with IV contrast can reliably exclude liver and spleen injuries requiring emergent operative intervention 2
• Chest trauma: Contrast-enhanced CT is superior for detecting vascular injuries and solid organ damage 2
• Penetrating trauma: CTA provides critical information about the source of active bleeding in hemodynamically stable patients 2

When Non-Contrast CT May Be Appropriate

• Hemodynamic instability: In severely unstable patients requiring immediate surgical intervention, non-contrast CT may be used if imaging is deemed necessary and cannot be delayed 2
• Contrast allergy: In patients with severe contrast allergies where premedication is not possible
• Renal insufficiency: In patients with severe renal dysfunction, though risk-benefit assessment should be made
• Limited indications: Non-contrast CT can effectively exclude pneumothorax and hemothorax but is limited in detecting solid organ injuries 2

Practical Considerations

Timing of Contrast Administration

• For optimal visualization of vascular structures and solid organ injuries, CT should be performed during:
  • Arterial phase (20-30 seconds delay) for vascular injuries
  • Portal venous phase (70-80 seconds delay) for solid organ injuries 2
  • Consider adding delayed excretory phase (5-minute delay) when urinary tract injuries are suspected 2

Common Pitfalls to Avoid

• Inadequate contrast timing: Poor bolus timing can miss active extravasation
• Omitting IV contrast: May lead to missed injuries, particularly vascular injuries and solid organ lacerations
• Unnecessary triple-contrast studies: While triple-contrast CT (oral, IV, and rectal) has been used historically for penetrating trauma 3, current guidelines favor IV contrast alone for most trauma scenarios

Special Considerations

Multi-phase Imaging

• In hemodynamically stable patients with suspected active bleeding, multi-phase imaging (arterial and venous phases) can provide additional information about the source and nature of bleeding 2

CT Without and With Contrast

• The addition of a non-contrast phase to contrast-enhanced CT does not provide additional information pertinent to penetrating trauma 2 and unnecessarily increases radiation exposure

Conclusion

Based on the most recent guidelines, CT scans for trauma workup should be performed with IV contrast to maximize detection of injuries and guide appropriate management. Non-contrast CT has limited utility in trauma evaluation except in specific circumstances where contrast administration is contraindicated or in limited applications such as detecting pneumothorax or hemothorax.