Calculators & Tools

CATCH Rule (Paediatric Head Injury)

Canadian Assessment of Tomography for Childhood Head injury - who needs a CT after minor head injury.

1 What is the CATCH Rule (Paediatric Head Injury)?

The CATCH Rule (Paediatric Head Injury) is a Neurology & trauma scoring tool used in paediatric practice. Canadian Assessment of Tomography for Childhood Head injury - who needs a CT after minor head injury. It scores 7 criteria and interprets the total across 3 bands, so the number always arrives with the severity it implies rather than on its own. In PediAid each criterion is shown as a labelled option with the weight it carries, so the total can be checked rather than taken on trust.

2 When to use it

  • Grading severity at the bedside in Neurology & trauma
  • Recording an objective severity band in the case notes
  • Deciding when a total crosses the threshold for escalation
  • Re-scoring to track whether a child is improving or deteriorating
  • Checking the exact criteria of a score used infrequently

3 Formula & method

The score sums 7 criteria: HIGH - GCS < 15 at two hours after injury; HIGH - Suspected open or depressed skull fracture; HIGH - Worsening headache; HIGH - Irritability on examination; MEDIUM - Any sign of basal skull fracture; MEDIUM - Large, boggy scalp haematoma; MEDIUM - Dangerous mechanism of injury. Totals are then banded: any score - CT not indicated: no high- or medium-risk factors - CT head not indicated by the CATCH rule. Observe and give head-injury advice; 1 risk factor or more - Medium risk - consider CT: medium-risk factor present - CT is recommended to detect brain injury on imaging (sensitivity ~98% for the full rule); 4 risk factors or more - High risk - CT required: high-risk factor present - CT head required; predicts need for neurological intervention (sensitivity 100% in the derivation cohort).
  • Applies to minor head injury: witnessed LOC, amnesia, disorientation, persistent vomiting or persistent irritability, with GCS 13-15.
  • Dangerous mechanism: MVC, fall from ≥0.9 m (3 ft) or 5 stairs, fall from a bicycle with no helmet.
  • Source: Osmond MH et al. CATCH: a clinical decision rule for the use of computed tomography in children with minor head injury. CMAJ 2010;182:341-8.

4 Frequently asked questions

How many criteria does the CATCH Rule (Paediatric Head Injury) use?

7. They are HIGH - GCS < 15 at two hours after injury; HIGH - Suspected open or depressed skull fracture; HIGH - Worsening headache; HIGH - Irritability on examination; MEDIUM - Any sign of basal skull fracture; MEDIUM - Large, boggy scalp haematoma; and others.

What do the bands of the CATCH Rule (Paediatric Head Injury) mean?

The total is interpreted as: any score - CT not indicated: no high- or medium-risk factors - CT head not indicated by the CATCH rule. Observe and give head-injury advice; 1 risk factor or more - Medium risk - consider CT: medium-risk factor present - CT is recommended to detect brain injury on imaging (sensitivity ~98% for the full rule); 4 risk factors or more - High risk - CT required: high-risk factor present - CT head required; predicts need for neurological intervention (sensitivity 100% in the derivation cohort).

Does the score replace clinical judgement?

No. It is a structured way to record and communicate severity. A clinician concerned about a child should act on that concern regardless of the total.

Where does this score come from?

Applies to minor head injury: witnessed LOC, amnesia, disorientation, persistent vomiting or persistent irritability, with GCS 13-15.

Does it work offline?

Yes. Score definitions are bundled with the PediAid app, so the score computes without a connection.

For qualified clinicians. This page and the PediAid app are a clinical aid only. Calculations and reference data must be verified against the patient's clinical context, the source guideline and your local protocols before any treatment decision is made.