PECARN Head Injury (< 2y) Calculator

PECARN Head Injury (< 2y) Calculator for Pediatrics. The rule yields three action tiers. A child with none of the six predictors is very low risk (ciTBI risk roughly 0.02 percent), and CT can be routinely avoided. A child with any of the two higher-weight findings (abnormal mental status or a palpable/uncertain skull fracture) is high risk, with ciTBI rates near 4.4 percent, and CT is recommended. A child with only an isolated occipital/parietal/temporal hematoma, isolated LOC of 5 seconds or more, severe mechanism, or not acting normally per parents is intermediate risk (roughly 0.9 percent), where CT versus a period of structured observation is chosen based on clinician experience, multiple versus isolated findings, worsening symptoms, age under 3 months, and parental preference.

How this calculator works

The PECARN rule for children under 2 years is an age-specific decision tree, not a summed point score, derived from the 8,502-child derivation cohort of the Kuppermann 2009 study. It assesses six clinical predictors: abnormal mental status (GCS 14 or agitation/somnolence/repetitive questioning/slow responses), an occipital, parietal, or temporal scalp hematoma, loss of consciousness of 5 seconds or longer, a palpable or unclear skull fracture, a severe injury mechanism, and whether the parent reports the child is not acting normally. The output stratifies a child into one of three tiers that map directly to a management pathway rather than yielding a numeric risk value.

When to use this calculator

Apply this rule only to children younger than 2 years presenting within 24 hours of blunt head trauma with a GCS of 14 to 15, mirroring the enrolled population. It is designed to safely avoid CT in the lowest-risk children and reduce radiation exposure in an age group with high radiosensitivity and frequent need for sedation. Do not use it for penetrating trauma, known bleeding disorders or anticoagulation, ventricular shunts, suspected non-accidental trauma, or when a GCS below 14 or a focal neurologic deficit is present, as these fall outside the derivation cohort and warrant independent evaluation.

Inputs used

  • Mental status
  • Scalp hematoma
  • Loss of consciousness
  • Mechanism
  • Palpable skull fracture
  • Parent report of abnormal behavior

Clinical interpretation

The rule yields three action tiers. A child with none of the six predictors is very low risk (ciTBI risk roughly 0.02 percent), and CT can be routinely avoided. A child with any of the two higher-weight findings (abnormal mental status or a palpable/uncertain skull fracture) is high risk, with ciTBI rates near 4.4 percent, and CT is recommended. A child with only an isolated occipital/parietal/temporal hematoma, isolated LOC of 5 seconds or more, severe mechanism, or not acting normally per parents is intermediate risk (roughly 0.9 percent), where CT versus a period of structured observation is chosen based on clinician experience, multiple versus isolated findings, worsening symptoms, age under 3 months, and parental preference.

Worked example

A 14-month-old falls from a standing height, does not lose consciousness, has a GCS of 15, an isolated frontal scalp hematoma, no palpable skull fracture, and the parents state he is behaving normally. Because the only hematoma is frontal (which the rule explicitly excludes) and no other predictor is present, he is in the very-low-risk group where the risk of clinically-important TBI is about 0.02 percent and CT is not indicated. If instead he had a large parietal hematoma but nothing else, he would fall into the intermediate group where observation versus CT is an individualized decision.

Limitations and safety notes

In the original under-2 validation cohort and the later Australasian prospective validation the rule identified 100 percent of clinically-important TBIs, but the confidence intervals are wide because ciTBI is rare, so a very small residual miss rate cannot be excluded. It predicts clinically-important TBI (death, neurosurgery, intubation over 24 hours, or admission 2 or more nights), not any TBI on imaging, so isolated skull fractures or small non-operative bleeds can be present in a child classified as low risk. It was not validated for suspected abusive head trauma, where injuries are often occult, and it does not apply to anticoagulated children or those with a GCS below 14.

Frequently asked questions

Why is a frontal scalp hematoma treated differently from other hematomas?

The derivation data showed that non-frontal scalp hematomas (occipital, parietal, temporal) in this age group carry meaningfully higher odds of underlying intracranial injury, whereas isolated frontal hematomas do not raise ciTBI risk. Only non-frontal hematomas count as an intermediate-risk predictor; an isolated frontal hematoma keeps a child in the very-low-risk group.

Does a normal PECARN result rule out a skull fracture?

No. The rule was built to identify clinically-important TBI, not to detect isolated skull fractures or small subclinical bleeds. A very-low-risk child may still have a linear skull fracture that would not change management, which is precisely why routine CT is not recommended for that group.

How should the intermediate-risk group be managed?

There is no single correct answer by design. Structured observation for 4 to 6 hours is a validated alternative to immediate CT, and the choice should weigh whether findings are isolated or multiple, whether symptoms are worsening, age under 3 months, clinician experience, and parental preference. Observation often lets many of these children avoid CT and its associated sedation.

Can I use this rule for an infant with possible abusive head trauma?

No. The rule was not designed or validated for suspected non-accidental trauma, where intracranial injury is frequently occult and the history may be unreliable or misleading. Any concern for abuse warrants imaging and a full safeguarding evaluation independent of the PECARN pathway.

References

  • Kuppermann N, Holmes JF, Dayan PS, et al. Identification of children at very low risk of clinically-important brain injuries after head trauma: a prospective cohort study. Lancet. 2009. PMID: 19758692.
  • Babl FE, Borland ML, Phillips N, et al. Accuracy of PECARN, CATCH, and CHALICE head injury decision rules in children: a prospective cohort study. Lancet. 2017. PMID: 28410792.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: June 13, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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