NEW YORK (Reuters Health) - Not all kids need a CT scan after a blunt trauma to the abdomen, according to a new study that identifies seven key signs to help doctors decide when a scan is unnecessary.
CT scans are becoming commonplace in emergency rooms, but they aren't harmless. Each scan delivers a dose of radiation that slightly increases a person's long-term risk of cancer - a risk that's especially heightened for children.
The key, researchers said, is determining when a CT will help doctors make an important diagnosis - and is therefore worth the risk - and when it is unlikely to benefit a young patient's care.
"An abdominal CT is the highest CT exposure for kids, and the younger the kid, the higher the exposure," said Dr. James Holmes, who led the new study at the University of California, Davis School of Medicine.
"This is the big radiation risk, and (parents) need to be aware that if their child really needs the image, they should get it. But if there's no good reason, they shouldn't," Holmes told Reuters Health.
His team's study included just over 12,000 kids seen at one of 20 ERs after a car or bike crash, fall or other abdominal injury between 2007 and 2010.
Each doctor and hospital decided independently when to do an abdominal scan, and 45 percent of children ended up getting one while in the ER. Just over six percent of all kids had abdominal injuries spotted on a CT scan, and about one-quarter of those needed surgery, a blood transfusion or another intervention.
Based on kids' symptoms and who ended up needing treatment, Holmes and his colleagues designed a seven-point checklist to determine when a CT scan is not warranted:
When children had no seat belt marks or other clear trauma, no stomach tenderness or pain and no thinking problems, breathing issues or vomiting, just one in 1,000 ended up with an acute injury requiring treatment.
Still, one-quarter of kids in the study who fit those criteria received a CT in the ER, the researchers reported in the Annals of Emergency Medicine.
A CT scan to the abdomen and pelvis delivers a radiation dose of eight millisieverts - equal to about three years' worth of natural background radiation, or the combined radiation from 400 chest X-rays.
Holmes said that for an infant, the risk of developing cancer after a single abdominal and pelvic CT scan might be as high as 1 in 200. By adolescence, that risks drops to 1 in 1,000 or 1 in 1,500.
There are times when a CT scan is clearly warranted to help doctors find or rule out serious injuries such as a lacerated spleen or liver, Holmes said.
"You're looking at those things that need to be identified because they need therapy, either an operation to repair their gastrointestinal injury, or perhaps an embolization to repair a bleeding artery," he said.
In those cases, "You don't want to send that patient home, because if they need that therapy, they're not going to get it" - and waiting can make things worse.
But, Holmes said, parents should feel comfortable questioning a doctor's decision to perform a stomach CT scan on their child, given the potential risks.
SOURCE: bit.ly/WD6wKF Annals of Emergency Medicine, online February 4, 2013.