# PECARN Head Injury Rule Calculator

URL: https://speedycalculator.com/calculators/health/pecarn/
Last updated: 2026-10-30

> The PECARN calculator applies the Pediatric Emergency Care Applied Research Network rule for children with minor head trauma to identify those at very low risk of a clinically important brain injury who can safely avoid a CT scan.

## Inputs

- 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

- Recommendation

## Formula

```
High risk: altered mental status or skull fracture signs
Intermediate risk: any other age-specific predictor
Very low risk: no predictors
```

## Explanation

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

ItemAnswers and pointsAgeUnder 2 years = 1; 2 years or older = 2GCS below 15, or other signs of altered mental statusNo = 0; Yes = 1Palpable skull fracture (under 2) / signs of basilar skull fracture (2+)No = 0; Yes = 1Loss of consciousness (5+ seconds under 2; any for 2+)No = 0; Yes = 1Occipital, parietal or temporal scalp haematoma (under 2)No = 0; Yes = 1Severe mechanism of injuryNo = 0; Yes = 1Not acting normally per parent (under 2)No = 0; Yes = 1History of vomiting (2+)No = 0; Yes = 1Severe headache (2+)No = 0; Yes = 1

### Inputs explained

FieldWhat to enterAgeChoose one: Under 2 years, 2 years or olderGCS below 15, or other signs of altered mental statusChoose one: No, YesPalpable skull fracture (under 2) / signs of basilar skull fracture (2+)Choose one: No, YesLoss of consciousness (5+ seconds under 2; any for 2+)Choose one: No, YesOccipital, parietal or temporal scalp haematoma (under 2)Choose one: No, YesSevere mechanism of injuryChoose one: No, YesNot acting normally per parent (under 2)Choose one: No, YesHistory of vomiting (2+)Choose one: No, YesSevere 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.*

## 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.

## FAQ

**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.


## Sources

- [Kuppermann N et al. Identification of children at very low risk of clinically important brain injuries after head trauma. Lancet, 2009](https://pubmed.ncbi.nlm.nih.gov/19758692/)