🧠 Canadian CT Head Rule
Decide whether CT is needed after minor head injury with the Canadian CT Head Rule.
Canadian CT Head Rule
GCS < 15 at 2 h after injury
Suspected open/depressed skull fracture
Sign of basal skull fracture
≥ 2 episodes of vomiting
Age ≥ 65
Amnesia before impact ≥ 30 min
Dangerous mechanism
When to use
Reduce unnecessary CT in minor head injury (GCS 13–15).
How it works
CT if any high-risk (GCS < 15 at 2 h, suspected open/depressed or basal skull fracture, ≥ 2 vomits, age ≥ 65) or medium-risk (amnesia ≥ 30 min, dangerous mechanism) factor.
Key points
- Applies to witnessed LOC/amnesia/disorientation with GCS 13–15.
- Excludes anticoagulation, seizure and age < 16.
- High-risk factors predict neurosurgical intervention.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.