What are the PECARN (Pediatric Emergency Care Applied Research Network) guidelines for determining which pediatric patients with minor head trauma require a computed tomography (CT) scan?

PECARN Guidelines for Pediatric Head CT Decision-Making

Children meeting PECARN very low-risk criteria can safely forgo CT imaging entirely, with a validated sensitivity of 100% and negative predictive value of 100% for clinically important traumatic brain injury. 1, 2

Risk Stratification Framework

The PECARN rule stratifies pediatric patients with minor head trauma into three distinct risk categories based on age-specific clinical criteria:

Very Low Risk (CT NOT indicated)

Children ≥2 years of age:

• GCS of 15 2, 3
• Normal mental status 2, 3
• No signs of basilar skull fracture 2, 3
• No loss of consciousness 2, 3
• No vomiting 2, 3
• No severe mechanism of injury 2, 3
• No severe headache 2, 3
• Risk of clinically important TBI: <0.02% 2

Children <2 years of age:

• GCS of 15 1, 2
• No altered mental status 1, 2
• No palpable skull fracture 1, 2
• No nonfrontal scalp hematoma 1, 2
• Loss of consciousness ≤5 seconds 1, 2
• No severe mechanism of injury 1, 2
• Acting normally per parents 1, 2
• Risk of clinically important TBI: <0.02% 1, 2

Intermediate Risk (CT may be considered vs. observation)

Children ≥2 years of age:

• GCS of 15 1, 3
• Normal mental status 1, 3
• No basilar skull fracture 1, 3
• BUT presence of: loss of consciousness, vomiting, severe mechanism of injury, OR severe headache 1, 3
• Risk of significant injury: approximately 0.8% 1, 3

Children <2 years of age:

• GCS of 15 1, 3
• Normal mental status 1, 3
• No palpable skull fracture 1, 3
• BUT presence of: loss of consciousness >5 seconds, severe mechanism of injury, OR not acting normally per parent 1, 3
• Risk of significant injury: approximately 0.9% 1, 3

For intermediate-risk patients, consider clinical observation as an alternative to immediate CT, with imaging reserved for: 1, 2

• Parental preference for definitive evaluation 1
• Multiple risk factors present simultaneously 1
• Worsening clinical symptoms or signs during observation 1, 2
• Young infants where observational assessment is challenging 1
• Every additional hour of observation decreases CT utilization without delaying diagnosis 3

High Risk (CT strongly indicated)

All ages:

• GCS of 14 or other signs of altered mental status 2, 3
• Signs of basilar skull fracture 2, 3
• Risk of clinically important TBI: approximately 4.3% 2, 3

Validation and Performance

The PECARN rule has demonstrated exceptional diagnostic accuracy across multiple international validation studies:

• Sensitivity: 100% for identifying clinically important traumatic brain injury 1, 2, 4
• Negative predictive value: 100% in external validation cohorts 1, 2, 4
• Australian/New Zealand validation confirmed 100% NPV and 99-100% sensitivity across both age groups 2
• French multicenter validation showed 100% sensitivity (95% CI 66.4-100%) and 100% NPV (95% CI 99.7-100%) 4
• Dutch cohort demonstrated PECARN would reduce CT rates from 44% to 23.8-28.3% without missing injuries 5
• The rule performs accurately even in infants <3 months of age 6

Critical Clinical Pitfalls to Avoid

Do NOT obtain CT scans in very low-risk patients who meet all PECARN criteria, as this exposes children to unnecessary radiation without clinical benefit 2, 7. A recent study found that 70 low-risk patients with positive CT findings required no intervention, and only 1 of 319 intermediate-risk patients with CT abnormalities required intervention based on clinical changes, not imaging 7.

Do NOT obtain skull radiographs as they miss up to 50% of intracranial injuries and provide no information about brain parenchyma 1, 2, 3.

Do NOT apply PECARN criteria to suspected non-accidental trauma cases, as these require separate evaluation protocols with either CT or MRI regardless of clinical presentation 2, 3.

Do NOT use IV contrast for acute trauma CT, as contrast may obscure subtle hemorrhages 1, 3.

Do NOT delay imaging when high-risk features are present (such as post-traumatic seizures with loss of consciousness), as this represents a clear indication for immediate CT 3.

Imaging Technical Specifications When CT is Indicated

Perform non-contrast CT head using: 1, 2, 3

• Dedicated pediatric protocols tailored to patient size 1, 3
• ALARA radiation dose reduction principles 2, 3
• Multiplanar and 3D reconstructions to increase sensitivity for fractures and small hemorrhages 2, 3

Special Populations

Infants <3 months: The PECARN rule maintains 100% sensitivity and NPV in this vulnerable population, though a lower threshold for imaging is often recommended due to difficulties assessing subtle symptoms 6.

Post-traumatic seizures: Seizures represent a high-risk criterion requiring immediate CT imaging, with incidence of intracranial injury ranging from 2.4% in mild TBI to 28-83% in severe TBI 3.