CATCH (Canadian Assessment of Tomography for Childhood Head injury) Rule

Identifies children with minor head injury who need CT to detect clinically important brain injury.

GCS <15 at 2 hours after injury (high risk)

Suspected open or depressed skull fracture (high risk)

History of worsening headache (high risk)

Irritability on examination (high risk)

Any sign of basal skull fracture – CSF otorrhea/rhinorrhea, hemotympanum, raccoon eyes, Battle's sign (medium risk)

Large, boggy scalp hematoma (medium risk)

Dangerous mechanism – MVC, fall from ≥3 ft/5 stairs, or fall from bicycle without helmet (medium risk)

ResultCT not required by CATCH

No high-risk or medium-risk predictors present.

When to use

Children under 16 years with minor head injury (GCS 13-15) presenting within 24 hours of injury, to decide whether CT is needed.

Formula

Any one of 4 high-risk criteria (predicting need for neurologic intervention) or 3 medium-risk criteria (predicting brain injury on CT) present → CT recommended.

Pearls and pitfalls

High-risk criteria were designed to be 100% sensitive for the need for neurosurgical intervention in the derivation cohort.
Not intended for infants under 6 months, penetrating trauma, or patients with a bleeding disorder.

References

Osmond MH, Klassen TP, Wells GA, et al. CATCH: a clinical decision rule for the use of computed tomography in children with minor head injury. CMAJ. 2010;182(4):341-348.