Head CT Indication in This Patient
Two episodes of vomiting is the primary indication for head CT in this patient with loss of consciousness after head trauma. 1
Clinical Decision Framework
According to the American College of Emergency Physicians Level A guidelines, a noncontrast head CT is indicated in head trauma patients with loss of consciousness when any one of the following features is present: 1
- Vomiting (present in this case - 2 episodes)
- Headache (present - moderate)
- Age greater than 60 years (not specified if met)
- Drug or alcohol intoxication
- Deficits in short-term memory
- Physical evidence of trauma above the clavicle (present - occipital hematoma)
- Posttraumatic seizure
- GCS score less than 15
- Focal neurologic deficit
- Coagulopathy
Why Vomiting is the Key Indicator
Vomiting carries particular weight in clinical decision rules. The Canadian CT Head Rule specifically identifies vomiting ≥2 episodes as a high-risk factor requiring CT imaging, with this criterion validated to have 100% sensitivity for identifying neurosurgical lesions. 1
- Miller et al demonstrated that vomiting had a positive predictive value of 100% for patients requiring neurosurgical intervention in their prospective study of 2,143 patients. 1
- Research confirms vomiting increases the odds ratio for abnormal CT findings to 1.89 (95% CI 1.23-2.80, P<0.001) in conscious head injury patients. 2
Why the Other Options Are Less Specific
Loss of consciousness alone is not an absolute indication for CT—it requires the presence of at least one additional risk factor from the list above. 1 While this patient has loss of consciousness, the specific indication triggering the CT requirement is the vomiting.
Nausea without vomiting is not included in any validated clinical decision rule (Canadian CT Head Rule or New Orleans Criteria) as an independent indication for CT. 1
Age becomes a CT indication at >60 years (New Orleans Criteria) or ≥65 years (Canadian CT Head Rule). 1 The patient's age is not specified in this scenario, making it an uncertain factor.
Clinical Context
This patient meets multiple criteria for CT imaging beyond just vomiting: 1
- Loss of consciousness (requires ≥1 additional risk factor)
- Two episodes of vomiting (high-risk criterion)
- Moderate headache (risk factor)
- Physical trauma above clavicle (occipital hematoma)
The combination of these findings places this patient at significant risk for intracranial injury, with studies showing up to 15% of mild TBI patients with GCS 14-15 have acute intracranial injury on CT, and 1% require neurosurgical intervention. 1
The presence of two vomiting episodes specifically elevates this patient to high-risk status requiring immediate CT imaging. 1