What is the PECARN (Pediatric Emergency Care Applied Research Network) rule for determining the need for a computed tomography (CT) scan in children with minor head trauma?

PECARN Rule for Pediatric Head Trauma

The PECARN rule is a highly validated clinical decision tool that stratifies children with minor blunt head trauma into very low, intermediate, and high-risk categories to guide CT imaging decisions, with 100% sensitivity for identifying clinically important traumatic brain injuries in children meeting very low-risk criteria. 1

Risk Stratification Framework

The PECARN rule divides patients into two age groups with distinct criteria:

Children ≥2 Years of Age

Very Low Risk (CT NOT indicated):

• GCS of 15 1
• Normal mental status 1
• No signs of basilar skull fracture 1
• No loss of consciousness 1
• No vomiting 1
• No severe mechanism of injury 1
• No severe headache 1

The risk of clinically important traumatic brain injury in this group is <0.02%, with 99.9% negative predictive value and 96.8% sensitivity. 1

Intermediate Risk (CT vs. observation):

• GCS of 15 1
• Normal mental status 1
• No basilar skull fracture 1
• BUT presence of: loss of consciousness, vomiting, severe mechanism of injury, or severe headache 1

The risk of significant injury is approximately 0.8% in this group. 1

High Risk (CT indicated):

• GCS of 14 or other signs of altered mental status 2
• Signs of basilar skull fracture 2

The risk of clinically important traumatic brain injury is approximately 4.3%. 2

Children <2 Years of Age

Very Low Risk (CT NOT indicated):

• GCS of 15 1, 3
• Normal mental status 1, 3
• No palpable skull fracture 1, 3
• No nonfrontal scalp hematoma 1, 3
• Loss of consciousness ≤5 seconds 1, 3
• No severe mechanism of injury 1, 3
• Acting normally per parents 1, 3

The risk of clinically important traumatic brain injury is <0.02%, with 100% negative predictive value and 100% sensitivity. 1, 3

Intermediate Risk (CT vs. observation):

• 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

The risk of significant injury is approximately 0.9%. 1, 3

High Risk (CT indicated):

• GCS of 14 or other signs of altered mental status 2
• Palpable skull fracture 2

Validation and Performance

The PECARN rule has been extensively validated across multiple international studies:

• The original 2009 study included over 40,000 children and demonstrated exceptional sensitivity. 1
• A large Australian/New Zealand validation study confirmed 100% negative predictive value and 99-100% sensitivity across both age groups. 1
• Multiple independent validation studies in France, Italy, and Korea have confirmed 100% sensitivity for identifying clinically important traumatic brain injuries. 4, 5, 6
• The PECARN rule outperforms other clinical decision rules (CATCH, CHALICE, NEXUS) with higher sensitivity and fewer unnecessary CT scans. 1

Clinical Implementation Strategies

For Very Low-Risk Patients:

• CT imaging should be avoided entirely—these children can be safely discharged without imaging. 1, 3
• Provide written and verbal discharge instructions at 6th-7th grade reading level with font size ≥12 points. 3
• Educate parents about postconcussive symptoms including dizziness, nausea, vision problems, sensitivity to noise/light, mood changes, and sleep disturbances. 3
• Warn that 18% of patients who deteriorate do so between days 2-7 after injury. 3

For Intermediate-Risk Patients:

• Consider clinical observation as an alternative to immediate CT scanning. 1, 2
• Every additional hour of emergency department observation is associated with decreased CT utilization without delaying diagnosis of significant traumatic brain injury. 2, 7
• CT may be considered based on parental preference, multiple risk factors, worsening symptoms during observation, or difficulty assessing young infants. 1
• Planned observation reduces CT use by 80% (adjusted OR 0.2) in intermediate-risk patients without missing clinically important injuries. 7

For High-Risk Patients:

• Immediate non-contrast CT head is indicated. 2
• Use dedicated pediatric CT protocols with dose reduction following ALARA principles. 2
• Multiplanar and 3D reconstructions should be performed to increase sensitivity for fractures and small hemorrhages. 1

Critical Pitfalls to Avoid

• Do not obtain skull radiographs—up to 50% of intracranial injuries occur without fracture, making plain films insufficient. 1, 2
• Do not apply PECARN criteria to suspected non-accidental trauma cases—these require separate evaluation protocols. 1, 2
• Do not use IV contrast for acute trauma CT—contrast may obscure subtle hemorrhages. 1
• Do not obtain CT scans in very low-risk patients who meet all PECARN criteria—this exposes them to unnecessary radiation without clinical benefit. 2
• Do not use MRI in the acute setting—it requires longer acquisition time, safety screening, and often sedation in young children, making it impractical for emergency evaluation. 1

Imaging Technical Specifications

When CT is indicated:

• Perform without IV contrast 1, 2
• Use pediatric-specific, size-adjusted protocols 1, 2
• Include multiplanar and 3D reconstructions 1, 2
• Follow ALARA radiation dose reduction principles 2

Disposition Decisions

Safe for Discharge:

• Negative CT scan with normal neurologic examination (100% negative predictive value for deterioration requiring surgery) 3
• Very low-risk patients without CT imaging 3

Requires Hospitalization:

• Positive CT findings showing intracranial injury 3
• Abnormal neurologic examination 3
• Patients on anticoagulation or antiplatelet therapy 3