Canadian CT Head Rule
Minor blunt head trauma ≥16 years; major then intermediate criteria of the original rule.
Canadian CT Head Rule
Principle
Blunt head trauma within 24 h, initial GCS 13–15, with loss of consciousness, definite amnesia or observed disorientation, age ≥16 years. Outside rule: minimal trauma without these signs, primary nontraumatic event, penetrating/obvious depressed fracture, acute focal deficit, unstable multiple trauma, seizure before assessment, bleeding disorder/oral anticoagulation, pregnancy or reassessment of the same head trauma. No automatic Glasgow transfer; do not delay care to wait two hours.
Scope
Blunt head trauma within 24 h, initial GCS 13–15, with loss of consciousness, definite amnesia or observed disorientation, age ≥16 years. Outside rule: minimal trauma without these signs, primary nontraumatic event, penetrating/obvious depressed fracture, acute focal deficit, unstable multiple trauma, seizure before assessment, bleeding disorder/oral anticoagulation, pregnancy or reassessment of the same head trauma. No automatic Glasgow transfer; do not delay care to wait two hours.
Interpretation limits
Blunt head trauma within 24 h, initial GCS 13–15, with loss of consciousness, definite amnesia or observed disorientation, age ≥16 years. Outside rule: minimal trauma without these signs, primary nontraumatic event, penetrating/obvious depressed fracture, acute focal deficit, unstable multiple trauma, seizure before assessment, bleeding disorder/oral anticoagulation, pregnancy or reassessment of the same head trauma. No automatic Glasgow transfer; do not delay care to wait two hours.
Formula and logic
Major criterion: age ≥65 OR suspected fracture OR basal skull sign OR vomiting ≥2 OR GCS <15 two hours after injury. Otherwise: amnesia before impact >30minutes OR dangerous mechanism. Without these criteria, the rule does not indicate CT.
Interpretation
- CT not indicated by the rule
- No criterion present in the eligible population; decisions and monitoring remain clinical.
- Intermediate criterion present
- Risk of clinically important intracranial injury; CT or close observation depending on assessment and resources, in the original2001 version.
- Major CT criterion present
- A high-risk criterion for neurological intervention is present; CT indicated according to the original rule.
Definition version : 0.1.0
Sources
- Stiell et al. · The Lancet — The Canadian CT Head Rule for patients with minor head injury
2001-05-05 · Full original text; methods, Panel1 and discussion reread, Panel1 visually inspected on 2026-10-06. Original thresholds ≥65 years, ≥2 vomiting episodes, amnesia >30min; GCS two hours after injury. No NICE variant added.