Pediatric NEXUS II Head CT Decision Instrument for Blunt Trauma

Apply the Pediatric NEXUS II Head CT Decision Instrument: seven blunt trauma criteria for children under 18 within 24 hours. Head CT supported when any criterion is positive. Educational tool.

Pediatric NEXUS II Head CT Decision Instrument

Pediatric blunt head trauma

For patients under 18 years with blunt head trauma within 24 hours when head CT is being considered. Mark any present findings. Head CT is recommended when any criterion is positive.

Age (years) *

Must be under 18 years per instrument scope.

Evidence of skull fracture (e.g. periorbital or periauricular bruising, hemotympanum, rhinorrhea or otorrhea of clear fluid, palpable step-off, stellate laceration)

Scalp hematoma involving the calvarium (face or neck hematomas without calvarial involvement do not count)

Neurologic deficit on examination

Abnormal level of alertness (e.g. GCS ≤14, delayed response, excessive sleepiness, disorientation, impaired recall of three objects at five minutes, perseveration)

Abnormal behavior (e.g. severe agitation, inconsolability, refusal to cooperate, flat affect, violent activity)

Persistent vomiting: more than one episode of forceful or projectile vomiting after injury

Coagulopathy (e.g. hemophilia, warfarin or other anticoagulants, aspirin or antiplatelet drugs, hepatic insufficiency)

Disclaimer: Educational tool only. Not a substitute for clinical judgment or site protocols. Low-risk pediatric head injury pathways often use PECARN or other validated rules; use this instrument in the population and context for which it was studied.

Pediatric NEXUS II explained

Pediatric NEXUS II Head CT Decision Instrument

This instrument applies to children under 18 years with blunt head trauma within the past 24 hours when non-contrast head CT is being considered. If any of the criteria below are present, the instrument supports obtaining head CT. If none are present, CT is not indicated by this rule alone (clinical judgment and other validated tools still apply).

Reference: Gupta M, Mower WR, Rodriguez RM, Hendey GW. Validation of the Pediatric NEXUS II Head Computed Tomography Decision Instrument for Selective Imaging of Pediatric Patients with Blunt Head Trauma. Acad Emerg Med. 2018 Jul;25(7):729-737. PMID 29665151.

Criteria (any one: positive screen, CT recommended by this instrument)

Evidence of skull fracture, for example periorbital or periauricular ecchymoses, hemotympanum, clear fluid from ears or nose, palpable step-off, or stellate scalp laceration.
Scalp hematoma involving the calvarium. Hematomas limited to the face or neck without calvarial involvement do not count as this criterion.
Neurologic deficit on detailed neurologic examination.
Abnormal level of alertness, for example GCS 14 or less, delayed or inappropriate responses, excessive somnolence, disorientation, impaired recall of three objects at five minutes, or perseveration.
Abnormal behavior, for example severe agitation, inconsolability, refusal to cooperate, flat affect, or violent activity.
Persistent vomiting: more than one episode of forceful or projectile emesis after injury (observed or by history).
Coagulopathy, for example hemophilia, therapeutic anticoagulation or antiplatelet drugs, or hepatic insufficiency affecting clotting.

Interpretation

Positive (any criterion): non-contrast head CT is recommended by this decision instrument.
Negative (no criteria): CT is not indicated by this instrument; observe, counsel on concussion and return precautions, and use clinical judgment. Many clinicians prefer externally validated rules such as PECARN for low-risk stratification when appropriate.

Limitations

The derivation cohort included children in whom clinicians were already considering head CT, which may differ from all-comers with minor head injury.
Does not replace bedside judgment, caregiver concern, imaging protocols, or guidelines that recommend tools such as PECARN for many scenarios.

Purpose and intended setting

The Pediatric NEXUS II Head CT Decision Instrument is a structured checklist used when clinicians are already weighing non-contrast head computed tomography after blunt head trauma. In this implementation it applies to patients under 18 years of age with injury within the prior 24 hours, aligned with the calculator scope encoded in the application.

The instrument does not estimate absolute risk percentages by itself. It operationalizes a simple rule: if any listed high-risk feature is present, imaging with head CT is supported by the rule. If none are present, this instrument alone does not endorse CT; further management relies on observation, shared decision-making, and often other validated pediatric head injury protocols used at many centers.

Decision logic

Evaluate each criterion as present or absent based on history and examination at the time of assessment. The screen is positive when one or more criteria are met. A positive screen means the decision instrument supports proceeding with non-contrast head CT. A negative screen means CT is not indicated by this instrument alone, which is not the same as declaring zero intracranial injury risk.

The seven criteria

Below, each item uses the same labels as the calculator. Clinical wording follows commonly published descriptions for this instrument.

1. Evidence of skull fracture

Consider battle signs, raccoon eyes, hemotympanum, cerebrospinal fluid leakage from the ears or nose, palpable calvarial deformity, or certain scalp injury patterns that raise concern for underlying fracture, such as stellate lacerations. Correlation with mechanism and examination findings remains essential because subtle fractures may not be obvious on initial inspection.

2. Scalp hematoma involving the calvarium

Soft-tissue bleeding over the skull vault counts toward this item. Bruising or swelling confined to the face or neck without calvarial involvement does not satisfy the criterion as specified for this rule. Location, size, and age-related scalp characteristics influence how clinically meaningful a hematoma appears.

3. Neurologic deficit

Focal findings on a structured neurologic examination (for example asymmetric strength, abnormal reflexes, cranial nerve abnormalities, or clear gait disturbance when testable) qualify. Transient symptoms reported only by history may still prompt escalation depending on context even when the formal instrument line item is negative.

4. Abnormal level of alertness

This domain captures altered consciousness beyond the child’s baseline. Examples include Glasgow Coma Scale scores in the 14 range or lower when fully assessed, somnolence out of proportion to setting, disorientation, impaired registration or recall on brief cognitive checks when age-appropriate, perseveration, or clearly inappropriate responsiveness. Pediatric adjustments for developmental stage apply when interpreting behavior.

5. Abnormal behavior

Severe agitation, inconsolability, refusal to engage when that is a marked change, flat affect, or violent behavior may satisfy this criterion when interpreted as a departure from expected post-injury behavior for that child. Caregiver testimony about personality change can supplement direct observation.

6. Persistent vomiting

The instrument targets repeated emesis: more than one episode of forceful or projectile vomiting after injury, whether witnessed or obtained reliably by history. A single episode of vomiting has different implications in many pathways and does not meet this specific definition.

7. Coagulopathy

Bleeding diathesis increases concern for expanding hematoma. Include inherited disorders such as hemophilia, therapeutic anticoagulation or antiplatelet medication, significant liver dysfunction affecting synthesis of clotting factors, and other conditions that materially impair hemostasis per clinical judgment and available laboratory data.

What a negative screen does and does not mean

When no criteria are positive, NEXUS II does not recommend CT based solely on the instrument. Many emergency departments still apply separate pediatric minor head injury rules (for example age-stratified algorithms that assign risk from mechanism, scalp findings, and Glasgow Coma Scale patterns) because those tools were derived for different inclusion criteria and outcomes. A negative NEXUS II screen should not silence caregiver concern, new symptoms, or protocol-mandated observation periods.

Relationship to imaging stewardship

Radiation exposure, throughput, sedation needs, and medicolegal context all influence real-world imaging decisions. Decision instruments reduce unstructured variation but never replace examination trends, social determinants of transport and follow-up, and shared safety-net instructions for return for worsening headache, repeated vomiting, seizure, or behavior change.

Limitations inherent to the framework

Study populations for clinical decision rules often reflect patients in whom providers already considered CT, which can skew performance compared with all minor head injury presentations. Sensitivity and specificity for clinically important traumatic brain injury depend on prevalence and operator consistency when coding each criterion.

Young infants, communicating barriers, neurodevelopmental conditions, and intoxication analogues in children complicate scoring alertness and behavior domains. Coagulopathy may be present before international normalized ratio or platelet results return. Finally, penetrating trauma, non-accidental injury concern, and injuries outside the blunt mechanism window fall outside the scenario this calculator models.