Dr. Brian Yu did a great 5-minute summary on the PECARN head CT Rule that was published in 2009. It’s an ambitious study that involved 25 emergency departments and included 42,412 patients under the age of 18 years who presented with blunt head trauma. It further risk stratified these patients into 2 major cohorts of <2 years of age and 2-18 years of age. It excluded patients with trivial injury, penetrating trauma, neurologic history, and those with prior imaging. The outcomes this study aimed for were clinically important findings including death, need for neurosurgical intervention, intubation >24 hours, and admission >2 nights. 

Using these 42,412 patients, they were able to identify 7 predictors that could safely predict a patient not needing a Head CT, which can be seen below.

&lt;2yoa2-18 yoa

This study had a NPV 100% in <2 years of age and NPV 99.95% in 2-18 years of age. It’s also important to note on the <2 yoa flowsheet that infants <3 months are part of the “shared decision-making” that may sway you to imaging. Also that the severe mechanism of injury in this cohort is a fall of 3 feet which could be from the height of a bed or from being held in arms. Lastly, it’s important to note that the risk of cancer from CT radiation in pediatrics is estimated at around 1 in 5,000. Therefore, we can use these risks when discussing our rationale for imaging with our patients.


Kuppermann N. 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):1160-1170. Link to Study

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