Canadian CT Head Rule
Canadian CT Head Rule — for minor head injury (GCS 13-15 with witnessed loss of consciousness, amnesia, or disorientation).
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- GCS < 15 at 2 h post-injury
- Yes
Result: CT head recommended — high-risk (neurosurgical): GCS < 15 at 2 h post-injury.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Any criterion
- CT head recommended — any of five high-risk (neurosurgical) or two medium-risk (clinically important) criteria present. Sensitivity-first rule that safely reduces head CT in minor head injury.
- None
- CT not required by the rule when all seven criteria are absent. A risk category, not an imaging order.
What you enter
- GCS < 15 at 2 h post-injury (high-risk)
- Suspected open or depressed skull fracture (high-risk)
- Any sign of basal skull fracture (high-risk)
- >= 2 episodes of vomiting (high-risk)
- Age >= 65 years (high-risk)
- Retrograde amnesia >= 30 min before impact (medium-risk)
- Dangerous mechanism (medium-risk)
How this is calculated
Stiell IG, Wells GA, Vandemheen K, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001;357(9266):1391-1396. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.