Free PECARN Calculator

PECARN Calculator for Pediatric TBI Risk Assessment

The free PECARN calculator provides clinicians with a quick, evidence-based method for evaluating traumatic brain injury (TBI) risk in children who have sustained head trauma. This online tool applies the Pediatric Emergency Care Applied Research Network (PECARN) rule—a widely validated decision algorithm for pediatric head injury—and is specifically designed to guide the decision of whether to obtain a head CT. By flagging patients at very low risk for clinically important TBI, the calculator helps reduce unnecessary radiation exposure while maintaining high sensitivity for injuries that require intervention.

The Origin and Purpose of the PECARN Rule

PECARN (Pediatric Emergency Care Applied Research Network) was the first multi-institutional research network entirely funded by the US federal government, with a focus on emergency care in children. Children are not small adults; their anatomy, physiology, and injury patterns differ significantly from those of adult patients, making adult trauma rules inappropriate for pediatric populations. To address this gap, PECARN conducted a large prospective study to develop age-specific criteria for head trauma assessment, resulting in the PECARN head injury rule that is now widely used in emergency departments.

Weighing CT Benefits Against Radiation Risks

Computed tomography is an incredibly valuable diagnostic technique, but it comes with a significant drawback: radiation exposure. A single head CT delivers a radiation dose equivalent to about 200 standard chest X-rays. A prominent Dutch cohort study revealed that children exposed to CT scans face up to a 47% increased risk of developing cancer later in life. This finding reinforces the importance of using validated decision aids like the PECARN CT decision rule to ensure CT scans are performed only when the potential benefit of detecting a serious brain injury clearly outweighs the lifelong carcinogenic risk.

Step-by-Step Application of the PECARN Criteria

Using the pediatric head trauma assessment tool requires answering up to three key clinical questions. The criteria are grouped into three assessment domains:

1. Physical Examination

• Measure the Glasgow Coma Scale (GCS) score; a GCS below 15 is a potential indicator of TBI.
• Palpate the skull for crepitus or a definite step-off that suggests fracture.
• Look for signs of basilar skull fracture:
  • Battle sign (ecchymosis over the mastoid process)
  • Raccoon eyes (periorbital ecchymosis)
  • Cerebrospinal fluid leakage from the nose or ears
  • Hemotympanum (blood behind the tympanic membrane)
• Assess for altered mental status (AMS), characterized by agitation, somnolence, slowed responses, or repetitive questioning.
• Note the presence and size of any scalp hematomas (especially in children under 2 years).

2. Medical History

• Document any loss of consciousness and its duration.
• Inquire about severe headache and episodes of vomiting (or intense nausea).
• Identify the injury mechanism. High-risk mechanisms include:
  • Motor vehicle collision involving a pedestrian or cyclist
  • An accident where another passenger died
  • Vehicular rollover or passenger ejection
  • Fall from greater than 3 feet (for younger children) or greater than 1 meter (for older children)
  • High-impact blow to the head, such as from a baseball or similar fast-moving object

3. Parental Observation Parents often detect subtle changes in their child’s behavior more readily than an examiner. Their report of any deviation from the child’s normal mental state is an important part of the overall assessment.

How the PECARN Algorithm Classifies Risk

The PECARN score for children stratifies patients into three risk tiers based on the presence or absence of the above clinical features. The algorithm defines two age groups (under 2 years and 2 years and older) with slightly different cutoff values. For the youngest patients, variables such as a large scalp hematoma or an altered mental status carry additional weight. The output is a classification of:

• Low risk (no CT indicated unless clinical deterioration)
• Intermediate risk (observation recommended; CT may be considered)
• High risk (CT indicated due to an elevated likelihood of clinically important TBI)

Limitations and Clinical Context

While the PECARN calculator is backed by high-quality evidence, it is not intended to replace a physician’s expertise. Clinical judgment should always incorporate additional factors—such as coexisting injuries, family preferences, and the child’s overall clinical trajectory—before making a final decision about imaging. This tool is best used as a rapid screening adjunct in busy emergency settings.