What are the indications for a computed tomography (CT) trauma scan in patients with severe injuries, including those with impaired mental status, such as a Glasgow Coma Scale (GCS) score of 13 or less, or those with signs of severe head, neck, chest, or abdominal trauma, including pediatric patients?

CT Trauma Scan Indications

For patients with severe injuries (GCS ≤13), obtain immediate non-contrast head CT and contrast-enhanced CT of chest, abdomen, and pelvis; for moderate injuries (GCS 9-13), obtain head CT and consider whole-body CT based on mechanism; for mild injuries (GCS 14-15), use validated clinical decision rules to determine need for selective imaging. 1

Severe Trauma (GCS ≤8)

Head CT is mandatory for all patients with GCS ≤8, performed immediately without delay. 1

• Non-contrast head CT is the first-line imaging test for detecting hemorrhage, cerebral edema, intracranial mass effect, and skull fractures 1
• CT bone algorithm reconstructions provide superior sensitivity for skull fractures compared to plain radiographs 1
• Intravenous contrast is not indicated for initial head CT 1

Consider whole-body CT (WBCT) for severe trauma based on mechanism and associated injuries. 1

High-velocity mechanisms warranting WBCT include:

• Motor vehicle collision >35 mph 1
• Rollover or passenger ejection 1
• Motorcycle trauma 1
• MVC-pedestrian collision 1
• Fall from height >15 feet 1

For chest, abdomen, and pelvis imaging, use CT with IV contrast as it has greater sensitivity for detecting visceral organ and vascular injury compared to non-contrast CT. 1

Moderate Trauma (GCS 9-13)

All patients with GCS 9-13 require brain CT scan. 1, 2

• Patients with GCS 13-14 have significantly higher rates of abnormal CT findings (12.4% for GCS 14,25% for GCS 13) compared to GCS 15 (3%) 1, 2
• These patients have higher incidence of skull fracture, delayed neurological deterioration, and need for neurosurgery 2
• GCS ≤13 is the optimal discrimination threshold for craniocerebral injuries in pediatric polytrauma 3

Consider WBCT versus selective imaging based on mechanism, hemodynamic stability, and initial portable radiographs/FAST results. 1

Mild Trauma (GCS 14-15)

Use validated clinical decision rules to determine CT indication rather than scanning all patients. 1, 4

High-Risk Criteria Requiring Immediate Head CT (GCS 14-15):

Any ONE of the following mandates head CT: 1, 5, 6

• GCS score <15 1, 5
• Loss of consciousness 1, 5
• Post-traumatic amnesia or short-term memory deficit 1, 5
• Vomiting (especially ≥2 episodes) 1, 5
• Severe headache 1, 5
• Age ≥60-65 years (with LOC or amnesia) 1, 5, 6
• Signs of basilar skull fracture (rhinorrhea, otorrhea, hemotympanum, Battle's sign, raccoon eyes) 1, 5
• Post-traumatic seizure 1, 5
• Focal neurologic deficit 1, 5
• Coagulopathy or anticoagulant therapy (warfarin, NOACs, clopidogrel, dual antiplatelet therapy—aspirin alone does NOT require routine CT) 1, 5
• Depressed or displaced skull fracture 1
• Dangerous mechanism (high-velocity MVC, pedestrian struck, fall from height) 1

Clinical Decision Rule Performance:

The most validated rules with near 100% sensitivity for neurosurgical lesions are: 4

• Canadian CT Head Rule: 99.1% sensitivity (95% CI 94-100%), requires CT in 56% of patients 4
• NEXUS-II: 100% sensitivity (95% CI 96-100%), requires CT in 56% of patients 4
• Scandinavian guideline: 99.1% sensitivity, highest specificity (52.9%), requires CT in only 50% of patients 4

Pediatric Considerations

For pediatric polytrauma, GCS ≤13 is the recommended threshold for head CT. 3

• Mechanism of injury alone does not predict injury severity in children 3
• Clinical examination and FAST have low sensitivity (<20%) for thoracic and abdominal pathologies 3
• CT is the diagnostic test of choice for moderate to severe pediatric head injury 7

Maxillofacial and Cervical Spine Imaging

Obtain non-contrast CT maxillofacial imaging for suspected osseous/soft-tissue facial injuries or skull base injuries. 1

• Often reconstructed from head and cervical spine source data 1
• Three-dimensional reformations improve surgical planning 1

Cervical spine CT should be obtained in moderate-to-severe TBI. 6

Initial Portable Radiography

Portable AP chest and pelvis radiographs serve as initial triage in unstable patients. 1

• Chest radiograph evaluates for tension pneumothorax, mediastinal injury, and confirms line placement 1
• Pelvis radiograph evaluates for unstable pelvic injuries and hip dislocation 1
• Abnormal chest radiograph in trauma has clinically significant rates of major injury on subsequent CT 1

FAST Ultrasound Role

FAST is primarily a triage tool; positive FAST with hemodynamic instability may lead directly to surgery rather than CT. 1

• Lower specificity compared to CT makes it insufficient to fully exclude injuries 1
• Should not replace CT in stable patients requiring definitive injury assessment 1

Critical Pitfalls to Avoid

Do not rely on normal neurologic examination alone to exclude significant injury in patients with risk factors. 1

• 1.7% of patients with GCS 15 and completely normal neurologic examination required neurosurgery 1
• Skull fracture increases risk of neurosurgical intervention 20-fold 1

Do not delay CT for "observation" in patients meeting high-risk criteria. 1

• Arterial hypotension (SBP <90 mmHg) and hypoxemia (SaO2 <90%) significantly worsen outcomes and must be corrected immediately 1

Repeat CT is indicated for: 1

• Secondary neurological deficit 1
• Decrease of ≥2 points in GCS 1
• Anticoagulated patients with initial hemorrhage (3-fold increased risk of progression: 26% vs 9%) 5

One-third of patients with normal admission CT develop new pathology within first few days, necessitating control scanning strategy in severe TBI. 8