The Canadian Assessment of Tomography for Childhood Head Injury (CATCH) rule can be used to help determine if a pediatric patient who has had a minor head injury should have a CT scan. This can help improve the efficiency of resource utilization without compromising patient care. The authors are from multiple Canadian Universities and Emergency Departments.


NOTE: This is based on the the Canadian CT Head Rule (CCHR) for Patients with Minor Head Injuries (see 29.23.01, above)


Age group: <= 16 years of age


Criteria for minor head injury:

(1) head injury within the past 24 hours

(2) initial Glasgow coma score 13 to 15

(3) one or more of the following:

(3a) witnessed loss of consciousness

(3b) definite amnesia

(3c) witnessed disorientation

(3d) persistent vomiting (2 or more episodes)

(3e) persistent irritability AND age < 2 years


Exclusion criteria:

(1) age > 16 years of age

(2) Glasgow coma score < 13

(3) obvious open or depressed skull fracture

(4) obvious penetrating head injury

(5) acute focal neurologic deficit

(6) chronic generalized developmental delay

(7) suspected child abuse

(8) pregnant

(9) return for reassessment


Rule: A CT scan is done if one or more medium and/or high risk factors are present.


Medium risk (for brain injury identified on CT scan)

(1) any sign of basal skull fracture

(2) large, boggy scalp hematoma

(2) dangerous mechanism



• A dangerous mechanism includes (1) motor vehicle crash, (2) fall from bicycle with no helmet, (3) fall from a height >= 3 feet, or (4) fall down stairs >= 5 steps

• Signs of basal skull fracture includes (1) hemotympanum, (2) "raccoon" eyes, (3) CSF otorrhea or rhinorrhea, or (4) Battle's sign

• raccoon eyes = periorbital ecchymosis

• Battle's sign = discoloration in the line of the posterior auricular artery, with ecchymosis first appearing near the tip of the mastoid process


High risk (for need of neurological intervention):

(1) GCS score < 15 at 2 hours after injury

(2) suspected open or depressed skull fracture

(3) history of worsening headaches

(4) irritability on examination



• Using the high risk criteria alone to identifying patients requiring neurological intervention: sensitivity 100%, specificity 70%, with proportion of patients with CT ordered 30%.

• Using the medium and high risk criteria to identifying patients requiring neurological intervention: sensitivity 98%, specificity 50%, with proportion of patients with CT ordered 52%.


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