USMLE Prep - Medical Reference Library

Pediatric Head Injury - PECARN Imaging Decision Rules

System: Pediatrics • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Use PECARN criteria to identify children at very low risk for clinically important traumatic brain injury and avoid unnecessary CT scans.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

For Pediatric Head Injury Pecarn Imaging, frame the differential by acuity and pathophysiology, then align diagnostics to the leading hypotheses. Prioritize stabilization while obtaining high‑yield studies such as CBC (Baseline hematology), BMP (Electrolytes/renal). Incorporate bedside imaging and targeted labs to define severity and identify complications; synthesize results with clinical trajectory to refine the working diagnosis and disposition needs.


Treatment Strategy & Disposition

Initiate disease‑directed therapy alongside supportive care, titrating to objective response. Pharmacologic options commonly include Analgesia/Antipyretics. Use validated frameworks (e.g., Red Flags for CT) to guide escalation and site of care. Address precipitating factors, de‑escalate empiric therapies with data, and arrange follow‑up for monitoring and risk‑factor modification; admit patients with instability, high risk of deterioration, or needs for close monitoring.


Epidemiology / Risk Factors

  • Risk factors vary by condition and patient profile

Investigations

TestRole / RationaleTypical FindingsNotes
CBCBaseline hematologyAbnormal counts
BMPElectrolytes/renalDerangements

Red Flags for CT

FindingRationale
Altered mental statusHigher risk of ciTBI
Severe mechanismHigher risk
Palpable skull fractureDirect indication

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Lorazepam (pre-procedure)GABA-A agonismHoursClaustrophobia/anxiety during imagingSedation
Prednisone + diphenhydramine (premed)Steroid + H1 blockerHoursOnly for prior contrast reactionHyperglycemia/sedation

Prognosis / Complications

  • Prognosis depends on severity, comorbidities, and timeliness of care

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

Notes

Shared decision making with families improves adherence. Document neurologic checks during observation.


References

  1. PECARN head trauma studies and tools — Link
  2. AAP guidance on pediatric head trauma — Link