NEXUS and PECARN c-spine

Apply the NEXUS low-risk criteria in adults, or the 2024 PECARN cervical spine rule in children aged 0–17, to decide whether blunt trauma needs cervical spine imaging and which type.

ENNL
Which rule
Criteria present

Tick what is present. All five absent means no imaging.

Outcome

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Factors present

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Work through the criteria

Tick what is present, then confirm you have assessed every point. An exclusion rule only works if you complete it: a single unassessed criterion makes the result worthless.

How to read the result

These are exclusion rules built for sensitivity, not specificity. They are good at identifying who can safely skip imaging, and deliberately poor at predicting who has an injury.

NEXUS, all five absentClear clinically; no imaging.
NEXUS, any criterion presentImaging indicated; modality per local protocol.
PECARN high riskConsider CT. Injury rate around 12%.
PECARN intermediate riskConsider radiographs. Injury rate around 3%.
PECARN, no risk factorsClinical clearance. Injury rate around 0.2%.

How the rules work

NEXUS: five criteria. All absent means no imaging; any present means imaging is indicated.

PECARN: nine risk factors in two tiers. Any high-risk factor leads to CT, any intermediate factor to radiographs, and none to clinical clearance.

Both rules apply to blunt trauma only. Penetrating injury falls outside them.

Neither rule tells you what to do with a positive result beyond the imaging step; the clinical picture continues to lead.

When to use it

  • Deciding whether a blunt trauma patient needs cervical spine imaging at all.
  • Justifying a decision not to image, where a documented rule carries more weight than a description.
  • Choosing between CT and radiographs in a child, which the PECARN rule addresses and NEXUS does not.
  • Reviewing a request for a cervical CT that does not obviously meet criteria.

⚠️ Pitfalls

  • "Distracting injury" was never precisely defined in NEXUS and remains the weakest link. When in doubt, count it as present.
  • NEXUS performs less well in older patients after low-energy falls. The Canadian C-Spine Rule excludes patients over 65 from clinical clearance altogether.
  • In PECARN, "substantial" head or torso injury means injury warranting admission or surgery, not injury that merely looks severe.
  • Children have a higher rate of SCIWORA than adults. A negative CT does not exclude cord injury where the examination suggests it.
  • Both rules assume a cooperative, assessable patient. They cannot be applied meaningfully through a sedated or intubated examination.

Frequently asked questions

What are the five NEXUS criteria?

Posterior midline cervical tenderness, evidence of intoxication, altered alertness, focal neurological deficit, and painful distracting injury. Imaging can be omitted only when all five are absent.

How sensitive is NEXUS?

In the original validation the rule identified around 99% of clinically significant cervical spine injuries, with a very high negative predictive value. Its specificity is low by design.

Can NEXUS be used in children?

It was not well validated in young children, and few children under eight were included. The 2024 PECARN cervical spine rule was derived and validated specifically in children aged 0 to 17 and is the better tool there.

What does the PECARN rule recommend?

CT when a high-risk factor is present, radiographs when only an intermediate-risk factor is present, and clinical clearance when none of the nine factors is present.

What counts as a substantial head or torso injury?

An injury warranting inpatient admission or surgical intervention. Examples given in the study include skull fracture, pneumothorax, signs of solid organ injury, thoracic, lumbar or sacral spine fracture, and pelvic fracture.

References

📄Hoffman JR, Mower WR, Wolfson AB, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. N Engl J Med. 2000;343(2):94–99.

📄Leonard JC, Harding M, Cook LJ, et al. PECARN prediction rule for cervical spine imaging of children presenting to the emergency department with blunt trauma. Lancet Child Adolesc Health. 2024;8(7):482–490.↗📄PECARN C-Spine Imaging Rule algorithm, 4 June 2024.↗

📄Stiell IG, et al. The Canadian C-spine rule for radiography in alert and stable trauma patients. JAMA. 2001;286(15):1841–1848.

This calculator supports clinical judgement and does not replace it. Always check the result against your own measurements and the guideline in force.

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