When does this rule apply?

Adults (≥16 years) with minor head injury: GCS 13–15, witnessed loss of consciousness, definite amnesia, or witnessed disorientation. NOT for patients on anticoagulants, open skull fracture, or seizure.

What are the high-risk criteria?

GCS <15 at 2h, suspected open/depressed skull fracture, ≥2 vomiting episodes, age ≥65. These predict need for neurosurgical intervention (100% sensitivity).

What are the medium-risk criteria?

Retrograde amnesia >30 minutes, dangerous mechanism (pedestrian struck, ejected from vehicle, fall >3 feet or >5 stairs). These predict brain injury detectable on CT.

Online Medical Tools — Canadian Head CT

Printed on 2/13/2026

For informational purposes only. This is not medical advice.

Emergency

Canadian Head CT

The Canadian CT Head Rule identifies patients with minor head injury (GCS 13–15) who require CT scanning. It uses high-risk criteria (for neurosurgical intervention) and medium-risk criteria (for brain injury on CT) to safely reduce unnecessary imaging while maintaining near-100% sensitivity for significant findings.

Compare with Glasgow Coma Scale

Formula: Decision rule with 4 high-risk and 2 medium-risk criteria. Any positive criterion = CT recommended.

Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.