Calculators & Tools

NEXUS II — Paediatric Head CT Rule

Identifies low-risk blunt head trauma where CT can be avoided. Any positive predictor = not low risk.

1 What is the NEXUS II — Paediatric Head CT Rule?

The NEXUS II — Paediatric Head CT Rule is a radiology scoring tool used in paediatric practice. Identifies low-risk blunt head trauma where CT can be avoided. Any positive predictor = not low risk. It scores 7 criteria and interprets the total across 2 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 radiology
  • 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: Evidence of significant skull fracture; Altered level of alertness; Neurological deficit; Persistent vomiting; Presence of scalp haematoma; Abnormal behaviour; Coagulopathy. Totals are then banded: any score - Low risk - CT may be avoided: no predictors - very low risk of clinically important intracranial injury (sensitivity ~98-100%). CT can reasonably be withheld with observation; 1 predictor or more - Not low risk: one or more predictors - NOT low risk. CT head is indicated, or observation with a low threshold to image.
  • Source: Oman JA et al. Performance of a decision rule to predict need for computed tomography among children with blunt head trauma (NEXUS II). Pediatrics 2006;117:e238-46.

4 Frequently asked questions

How many criteria does the NEXUS II — Paediatric Head CT Rule use?

7. They are Evidence of significant skull fracture; Altered level of alertness; Neurological deficit; Persistent vomiting; Presence of scalp haematoma; Abnormal behaviour; and others.

What do the bands of the NEXUS II — Paediatric Head CT Rule mean?

The total is interpreted as: any score - Low risk - CT may be avoided: no predictors - very low risk of clinically important intracranial injury (sensitivity ~98-100%). CT can reasonably be withheld with observation; 1 predictor or more - Not low risk: one or more predictors - NOT low risk. CT head is indicated, or observation with a low threshold to image.

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?

Source: Oman JA et al. Performance of a decision rule to predict need for computed tomography among children with blunt head trauma (NEXUS II). Pediatrics 2006;117:e238-46.

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.