Advanced Search
Discover new calcs: choose 1 function + 1 more filter
Click here to discover
Pulmonary Embolism
calculators for
After you diagnose a PE, discover
Pulmonary Embolism
calculators for

    Calc Function

  • Calcs that help predict probability of a diseaseDiagnosis
  • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
  • Disease is diagnosed: prognosticate to guide treatmentPrognosis
  • Numerical inputs and outputsFormula
  • Med treatment and moreTreatment
  • Suggested protocolsAlgorithm





Chief Complaint


Organ System


Canadian CT Head Injury/Trauma Rule

Clears head injury without imaging.

Only apply to:

Exclusion Criteria:

  • Age <16
  • Blood thinners
  • Seizure after injury
High Risk Criteria: Rules out need for neurosurgical intervention
Medium Risk Criteria: In addition to above, rules out “clinically important” brain injury (positive CT's that normally require admission)


  • Consider obtaining a CT scan if any questions in the rule are answered affirmatively.
  • This rule can only be applied to patients with LOC/Amnesia or changes in mental status.
  • The original study did not include subjects <16 years of age.


  • Remember to always discuss post-concussive symptoms and management with the patient, especially if discharging them without a head CT. Otherwise when they feel post-concussive symptoms they may worry a CT was necessary.
  • By educating them on the symptoms of injuries that require neurosurgical intervention vs. post-concussive symptoms, the patient can feel empowered and reassured.

Critical Actions

The Canadian CT Head Rules have been validated in multiple settings and have consistently demonstrated that they are 100% sensitive for detecting injuries that will require neurosurgery.

  • Depending on practice environment, it may not be considered acceptable to miss any intracranial injuries, regardless of whether they would have required intervention.
  • Providers may want to consider applying the New Orleans Criteria (NOC) for head trauma, as there has been at least one trial finding it to be more sensitive for detecting clinically significant intracranial injuries (99.4% vs 87.3%). Though this comes at the price of markedly decreased specificity (5.6% vs. 39.7%).
    • Furthermore, there are other trials in which the CCHR was found to be more sensitive than the NOC for detecting clinically important brain injuries.
Content Contributors