Interactive implementation of the PECARN pediatric head injury decision rule
(Kuppermann et al., The Lancet, 2009): age-specific predictors for children
under 2 years and ages 2–17, ciTBI risk tiers, and CT guidance.
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Educational aid only — not medical advice. This tool does not replace
clinical judgment or a clinician’s examination. A head injury in a child can be an emergency.
Seek emergency care immediately (for example call 119 in Indonesia)
for danger signs: worsening headache, repeated vomiting, increasing sleepiness or difficulty waking,
seizure, unequal pupils, weakness, slurred speech, or behavior change after head trauma.
Interactive PECARN rule
Enter the child’s age, then tick every predictor that is present. Unticked = absent.
Rule: children younger than 2 years
~0.9%
Intermediate risk Children younger than 2 years
Decision aid, not a directive. The intermediate tier is assistive, not
prescriptive: observation versus CT is a shared decision between the clinician and the caregiver.
This calculator cannot examine the child — when in doubt, a clinician decides.
Worked examples (recomputed from the rule)
1 — 14-month-old, fall from a changing table (~1 m), occipital hematoma
No loss of consciousness, alert, acting normally per parent. Present predictors:
severe mechanism (fall > 3 ft for under-2) + non-frontal scalp hematoma (occipital).
Rule: under 2 → 2 intermediate predictors, no high-risk predictor →
intermediate tier, ciTBI risk ~0.9% → observation vs CT, shared clinician–caregiver decision.
2 — 5-year-old, vomited twice, severe headache after playground fall
No loss of consciousness, alert, no vomiting before the injury. Present predictors: vomiting +
severe headache. Rule: 2 and older → 2 intermediate predictors, no high-risk predictor →
intermediate tier, ciTBI risk ~0.8% → observation vs CT, shared clinician–caregiver decision.
The two rules side by side
Element
Children < 2 years
Children 2–17 years
High-risk predictor 1
Altered mental status
Altered mental status
High-risk predictor 2
Palpable skull fracture
Signs of basilar skull fracture
Intermediate predictor
LOC ≥ 5 seconds
Any LOC
Intermediate predictor
Severe mechanism (fall > 3 ft)
Severe mechanism (fall > 5 ft)
Intermediate predictor
Non-frontal scalp hematoma
Vomiting
Intermediate predictor
Not acting normally per parent
Severe headache
Low-risk ciTBI rate
< 0.02%
< 0.05%
Intermediate ciTBI rate
~0.9%
~0.8%
High-risk ciTBI rate
~4.4%
~4.3%
CT guidance
Low: CT not recommended · Intermediate: observation vs CT (shared decision) · High: CT recommended
Methodology
Rule selection: age < 24 months → under-2 rule ·
age ≥ 24 months → 2-and-older rule Tier: any high-risk predictor → high ·
any intermediate predictor (no high) → intermediate ·
none → low
Predictor structure per Kuppermann et al., “Identification of children at very low
risk of clinically-important brain injuries after head trauma: a prospective cohort study,”
The Lancet 2009;374(9696):1160–70 (n = 42,412; derivation 33,785 + validation 8,627; 376 ciTBI).
Validation performance: under-2 rule 100% sensitivity / 100% NPV; 2-and-older rule 96.8% sensitivity
(61/63) / 99.95% NPV (3,798/3,800). ciTBI = death from TBI, neurosurgical procedure, intubation > 24 h
for TBI, or admission ≥ 2 nights for TBI with TBI on CT. Predictor wording cross-checked against the
rule figures reproduced in Kwon et al. (Clin Exp Emerg Med 2021) and the 2024 multicenter validation
(Lancet Child & Adolescent Health).
Scope boundary: what this tool is (and isn’t)
This tool = the PECARN CT decision rule. History + examination predictors → ciTBI risk tier
→ CT guidance (not recommended / observation vs CT / recommended).
NOT a consciousness score. The
Glasgow Coma Scale calculator scores eye/verbal/motor
responses (3–15, incl. the paediatric variant) — a GCS of 14 is itself one PECARN predictor
(“altered mental status”). Score consciousness there; decide on imaging here.
NOT for every head injury. Excluded from the underlying study: GCS < 14, penetrating trauma,
known brain tumor, neurological disorders, trivial mechanisms, and suspected non-accidental trauma.
NOT a substitute for clinical judgment. The rule is assistive, especially in the intermediate
tier; the clinician and caregiver make the final call.
The PECARN rule is a validated clinical decision rule that identifies children at very low risk of clinically important traumatic brain injury (ciTBI) after blunt head trauma, to guide whether a head CT is needed. It was derived and validated by Kuppermann and colleagues in a prospective study of 42,412 children (The Lancet, 2009). It uses two separate algorithms — one for children younger than 2 years and one for children aged 2 to 17 years — each with six predictors.
Which children does the PECARN rule apply to?
The rule was studied in children under 18 who presented within 24 hours of blunt head trauma with a Glasgow Coma Scale score of 14 or 15. It does not apply to children with a GCS below 14, penetrating head trauma, known brain tumors, pre-existing neurological disorders, trivial injury mechanisms (for example a ground-level fall with only a scalp abrasion), or suspected non-accidental trauma (child abuse) — those situations need separate evaluation by a clinician.
What are the six predictors for children younger than 2 years?
For children under 2: (1) altered mental status and (2) palpable skull fracture — these two are high-risk predictors; plus (3) loss of consciousness lasting 5 seconds or more, (4) severe mechanism of injury, (5) non-frontal scalp hematoma (occipital, parietal, or temporal — a frontal-only hematoma does not count), and (6) not acting normally according to the parent. If none of the six is present, the child falls in the very-low-risk group.
What are the six predictors for children aged 2 years and older?
For children 2 and older: (1) altered mental status and (2) signs of basilar skull fracture — these two are high-risk predictors; plus (3) any loss of consciousness, (4) severe mechanism of injury, (5) vomiting, and (6) severe headache. Note the differences from the under-2 rule: any LOC counts (there is no 5-second threshold), and vomiting plus severe headache replace the hematoma and behavior items.
What counts as a “severe mechanism of injury”?
A motor-vehicle crash with patient ejection, death of another passenger, or rollover; a pedestrian or bicyclist without a helmet struck by a motorized vehicle; a fall from more than 3 feet (about 0.9 m) for children under 2, or more than 5 feet (about 1.5 m) for children 2 and older; or the head being struck by a high-impact object.
How does the result guide the CT decision?
Three tiers. High risk — any high-risk predictor present (about 4.4% ciTBI for children under 2, about 4.3% for children 2 and older, in the study cohorts): CT is recommended. Intermediate risk — any intermediate predictor but no high-risk predictor (about 0.9% for under 2, about 0.8% for ages 2 and older): the decision is shared between the clinician and the caregiver — observation without immediate CT is an option, with CT reserved for worsening symptoms, multiple predictors, or caregiver preference. Low risk — no predictor present (below 0.02% for under 2, below 0.05% for ages 2 and older): CT is not recommended.
What is clinically important traumatic brain injury (ciTBI)?
The study defined ciTBI as any of: death from the head injury; a neurosurgical procedure; intubation for more than 24 hours because of the head injury; or hospital admission for 2 or more nights for the head injury in association with traumatic brain injury seen on CT. The rule targets these outcomes that change management, not incidental CT findings that do not.
How well was the PECARN rule validated?
In the original study — 33,785 children in the derivation group and 8,627 in the validation group, with 376 ciTBI cases overall (0.9%) — the under-2 rule had 100% sensitivity and 100% negative predictive value for ciTBI in the validation group. The 2-and-older rule had 96.8% sensitivity (61 of 63 ciTBI cases detected) and 99.95% negative predictive value (3,798 of 3,800). A 2024 multicenter validation (The Lancet Child & Adolescent Health) again confirmed high accuracy.
How is PECARN different from the (paediatric) Glasgow Coma Scale?
They answer different questions. The Glasgow Coma Scale scores the level of consciousness from eye, verbal, and motor responses (total 3–15); the paediatric variant adapts the verbal and motor items for young children. PECARN is a CT decision rule: it combines history and examination predictors — including mechanism of injury, vomiting, and scalp hematoma, which the GCS does not assess — to estimate ciTBI risk and guide imaging. A GCS of 14 is itself one PECARN predictor (altered mental status). Use our Glasgow Coma Scale calculator to score consciousness, and this PECARN tool for the CT decision.
What happens during observation for the intermediate-risk group?
The child is watched in the emergency department for evolving symptoms — worsening headache, repeated vomiting, increasing sleepiness, or behavior change. Evidence discussed with the rule notes that each additional hour of observation lowers CT use without delaying diagnosis of injuries that need intervention. If symptoms worsen or several predictors are present, the clinician may proceed to CT; caregiver preference is explicitly part of the decision.
Which rule applies to a child who is exactly 2 years old?
The 2-and-older rule. The study’s age split places children from their second birthday onward in the older-child group — so at exactly 24 months, use the six predictors for children aged 2 and older: altered mental status, signs of basilar skull fracture, any loss of consciousness, severe mechanism of injury, vomiting, and severe headache. This calculator applies that boundary automatically.
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