About half of U.S. children taken to hospital emergency departments for a head injury receive a computer tomography (CT) scan, often to ease parents' concerns. But a new study shows that allowing a period of observation before undergoing the brain scan can reduce the use of CT by as much as half without compromising care -- and without exposing children to ionizing radiation.

"Only a small percentage of children with blunt head trauma really have something serious going on," Dr. Lise Nigrovic, of Children's Hospital Boston, said in a statement. "If you can be watched in the [emergency department] for a few hours, you may not need a CT."

This change in practice would not only save costs, but would be better medicine, the researchers said.

The study was published online today (May 9) in the journal Pediatrics.

Comparing risks

Researchers analyzed the health outcomes of children who visited 25 different emergency departments as part of a large study called the Pediatric Emergency Care Applied Research Network.

Of the 40,113 children whose records were analyzed about CT scan use, 5,433 of them were observed by doctors before undergoing the head CT scan (though observation times varied by case).

Overall, the children who were observed had a lower rate of CT than those not observed, 31 percent compared with 35 percent, the study said.

And when the researchers matched the observed and non-observed groups for severity of head injury and the practice style of different hospitals, this difference was more pronounced: The likelihood of a CT scan in the observed group was about half that of similar patients weren't observed. In particular, children whose symptoms improved during observation were less likely to eventually have CT.

However, allowing for an observation period did not compromise safety, according to the study. Clinically important traumatic brain injury -- resulting in death, neurosurgical intervention, intubation for more than 24 hours or hospital admission for two nights or more -- was equally uncommon in the observed groups (at 0.75 percent) and the non-observed groups (at 0.87 percent).

Are CT scans bad?

Head CT scans can be risky for children, researchers said. Children's growing brain tissue is more sensitive to ionizing radiation than adults', and because of their longer life expectancy, their lifetime risk of developing a radiation-induced cancer is greater.

"CT isn't bad if you really need [it], but you don't want to use it in children who are at low risk for having a significant injury," Nigrovic said. "For parents, this means spending a couple of extra hours in the [emergency department] in exchange for not getting a CT. It's the children in the middle-risk groups -- those who don't appear totally normal, but whose injury isn't obviously severe -- for whom observation can really help."

More research is needed to determine the length of time that is needed for children to be observed in the emergency department before a CT scan . Practice guidelines from the American Academy of Pediatrics recommend a child be carefully observed for four to six hours after injury.

Nigrovic offers the following general guidelines for parents whose child has a head injury:

  • Check with your primary care clinician before taking the child to the emergency department.
  • An emergency department visit is appropriate if your child has headache, vomiting or confusion, or symptoms that worsen over time.
  • The emergency department clinician may reasonably choose to observe your child for several hours once you arrive before deciding about a head CT.
  • The change of symptoms over time is an important factor in deciding whether to obtain a head CT scan.

Pass it on: For kids who receive a mild head injury, it is wise to allow a period of observation before undergoing a CT scan to see if they really need to be exposed to the radiation.

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