This version was machine-translated from German and has not been medically reviewed. The authoritative version is the German version.

CATCH & CATCH2 Head Injury Rule

Canadian CT rule for mild traumatic brain injury: four high-risk and three (CATCH2: four) medium-risk factors

High-risk factors (neurointervention)

GCS not 15 within 2 hours of the injury

Suspected open or depressed skull fracture

increasing headache

Irritability on examination

Intermediate-risk factors (brain injury on CT)

large, doughy cephalohematoma

Signs of a skull base fracture

dangerous mechanism (road traffic accident, fall ≥ 0.9 m or 5 stairs, fall from a bicycle without helmet)

≥ 4 episodes of vomiting (CATCH2)

Calculation aid for healthcare professionals: the calculator reproduces what the sources cited assign to the inputs. Clinical assessment and every treatment decision remain with the treating physician. Inputs and results are not stored.

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Sources

CATCH: a clinical decision rule for the use of computed tomography in children with minor head injury (CMAJ 182:341–348) Osmond MH, Klassen TP, Wells GA, et al.; Pediatric Emergency Research Canada (PERC) Head Injury Study Group, 2010. Original paper (freely accessible)
Validation and refinement of a clinical decision rule for the use of computed tomography in children with minor head injury in the emergency department (CMAJ 190:E816–E822) – CATCH2 Osmond MH, Klassen TP, Wells GA, et al., 2018. Validation study (open access)
Derivation of the children's head injury algorithm for the prediction of important clinical events decision rule for head injury in children (Arch Dis Child 91:885–891) – CHALICE Dunning J, Daly JP, Lomas JP, et al.; Children's Head Injury Algorithm for the Prediction of Important Clinical Events Study Group, 2006. Original paper (freely accessible)

Scientific basis last reviewed: September 2026.

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Note

Calculation aid for healthcare professionals. Percentiles and z-scores describe the position of a measured value in the reference population; clinical assessment remains with the treating physician.