The PECARN rule was derived and validated in over 42,000 children. Children with no high-risk features have a less than 0.05% risk of clinically important brain injury. Separate criteria apply to children under 2 and those 2 and over.
How to use the PECARN Head Injury Rule Calculator
- Age
- GCS below 15, or other signs of altered mental status
- Palpable skull fracture (under 2) / signs of basilar skull fracture (2+)
- Loss of consciousness (5+ seconds under 2; any for 2+)
- Occipital, parietal or temporal scalp haematoma (under 2)
- Severe mechanism of injury
- Not acting normally per parent (under 2)
- History of vomiting (2+)
- Severe headache (2+)
Results update as you type, and every field accepts the units shown in its menu.
How it works
Each answer carries the points shown in the published score. The calculator adds them up and maps the total to the published interpretation.
Scoring table
| Item | Answers and points |
|---|---|
| Age | Under 2 years = 1; 2 years or older = 2 |
| GCS below 15, or other signs of altered mental status | No = 0; Yes = 1 |
| Palpable skull fracture (under 2) / signs of basilar skull fracture (2+) | No = 0; Yes = 1 |
| Loss of consciousness (5+ seconds under 2; any for 2+) | No = 0; Yes = 1 |
| Occipital, parietal or temporal scalp haematoma (under 2) | No = 0; Yes = 1 |
| Severe mechanism of injury | No = 0; Yes = 1 |
| Not acting normally per parent (under 2) | No = 0; Yes = 1 |
| History of vomiting (2+) | No = 0; Yes = 1 |
| Severe headache (2+) | No = 0; Yes = 1 |
Inputs explained
| Field | What to enter |
|---|---|
| Age | Choose one: Under 2 years, 2 years or older |
| GCS below 15, or other signs of altered mental status | Choose one: No, Yes |
| Palpable skull fracture (under 2) / signs of basilar skull fracture (2+) | Choose one: No, Yes |
| Loss of consciousness (5+ seconds under 2; any for 2+) | Choose one: No, Yes |
| Occipital, parietal or temporal scalp haematoma (under 2) | Choose one: No, Yes |
| Severe mechanism of injury | Choose one: No, Yes |
| Not acting normally per parent (under 2) | Choose one: No, Yes |
| History of vomiting (2+) | Choose one: No, Yes |
| Severe headache (2+) | Choose one: No, Yes |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
High risk: altered mental status or skull fracture signs
Intermediate risk: any other age-specific predictor
Very low risk: no predictors
Worked example
Inputs — Age: 2 years or older; GCS below 15, or other signs of altered mental status: No; Palpable skull fracture (under 2) / signs of basilar skull fracture (2+): No; Loss of consciousness (5+ seconds under 2; any for 2+): No; Occipital, parietal or temporal scalp haematoma (under 2): No; Severe mechanism of injury: No; Not acting normally per parent (under 2): No; History of vomiting (2+): No; Severe headache (2+): No.
Results — Recommendation = Very low risk (< 0.05%) – CT not recommended.
Key terms
- GCS
- Glasgow Coma Scale.
- ciTBI
- Clinically important traumatic brain injury.
Frequently asked questions
Why avoid CT scans in children?
Radiation increases lifetime cancer risk, and most minor head injuries need no scan.
What is a severe mechanism?
E.g. a car crash with ejection, pedestrian struck, fall over 0.9 m (under 2) or 1.5 m (2+), or a head struck by a high-impact object.
Does PECARN apply to all head injuries?
It applies to children with GCS 14–15 within 24 hours of the injury.