Patient Inputs
Large screens show three columns, smaller screens two, and mobile one.
Example Data Table
| Case | Age | GCS 2h | Vomits | Amnesia | Dangerous Mechanism | Suggested Output |
|---|---|---|---|---|---|---|
| A | 72 | 15 | 0 | 10 min | No | CT recommended |
| B | 30 | 15 | 0 | 45 min | No | CT recommended |
| C | 24 | 15 | 0 | 0 min | No | CT not indicated by rule |
| D | 41 | 14 | 1 | 5 min | No | CT recommended |
Formula Used
The Canadian CT Head Rule is a clinical decision rule, not a numeric scoring system. The calculator applies eligibility filters first, then checks for rule-defined criteria.
- Applicable population: adult minor head injury with GCS 13–15, plus loss of consciousness, amnesia, or witnessed disorientation, presenting within 24 hours.
- High-risk criteria: GCS below 15 at 2 hours, suspected open or depressed skull fracture, basal skull fracture signs, at least two vomiting episodes, or age 65 years and above.
- Medium-risk criteria: retrograde amnesia for 30 minutes or more, or a dangerous mechanism.
- Decision logic: if any high-risk or any medium-risk criterion is present in an applicable patient, CT is recommended by the rule.
How to Use This Calculator
- Enter age, timing, arrival GCS, 2-hour GCS, vomiting count, and amnesia duration.
- Mark whether the patient had loss of consciousness, definite amnesia, or witnessed disorientation.
- Flag specific high-risk findings, fracture signs, dangerous mechanism, and exclusion conditions.
- Press Submit to show the recommendation above the form.
- Use the export buttons to save result summaries or example data.
- Do not use the output in children, anticoagulated patients, or other excluded presentations.
Frequently Asked Questions
1. What does this calculator decide?
It estimates whether head CT is recommended by the Canadian CT Head Rule for an adult with minor head injury who meets the rule’s application criteria.
2. Is this rule a point-based score?
No. It uses structured yes-or-no criteria. The result depends on applicability first, then on whether defined high-risk or medium-risk findings are present.
3. Can I use this for children?
No. The Canadian CT Head Rule excludes patients younger than 16 years. Pediatric head injury tools should be used instead.
4. Why are anticoagulant users marked as not applicable?
The original rule excluded patients with bleeding disorders or anticoagulant use. These patients need separate clinical assessment and local imaging guidance.
5. What counts as a dangerous mechanism?
Typical examples include pedestrian struck by a vehicle, occupant ejected from a vehicle, or a fall from more than 3 feet or 5 stairs.
6. Does one medium-risk factor trigger CT?
This calculator recommends CT when a rule-listed medium-risk factor is present in an applicable patient, while still separating medium-risk from high-risk findings in the output.
7. Should this replace emergency physician judgment?
No. It supports structured decision-making only. Overall trauma context, examination findings, observation needs, and local policy still matter.
8. Why is the result shown above the form?
That layout makes reassessment faster. Users can see the recommendation immediately after submission without scrolling past all inputs again.