Why are so many CT scans being done?

The Pediatric Insider

© 2013 Roy Benaroch, MD

As with all medical interventions and tests, CT scans have their pros and cons. You can get nifty pictures of the inside of skulls, and you can easily diagnose brain hemorrhages and skull fractures; while at the same time, you’re exposing the patient to ionizing radiation. In the long run, all of those CT scans add up. A fair estimate blames about 2% of the cancers in the United States as being caused by diagnostic radiation (mostly CT scans.) Now, maybe that’s a fair trade-off, if the CT scans are really necessary and really help diagnose and treat patients.

But it turns out that many CTs aren’t really necessary, and end up doing more harm than good.

One of the most common scenarios in pediatrics for a CT scan is as part of the evaluation of head trauma. Now, head trauma is a serious problem, and can lead to both short- and long-term disabilities, but obviously in the world of pediatrics most head bonks don’t lead to any serious problems at all. Little kids bonk their heads all the time, because they’re reckless and fall down; big kids bonk their heads on other big kids during sports. The trick is telling which head bonks are likely to lead to problems that need to be addressed immediately, and which head bonks have caused pathology that can be diagnosed and treated based on the findings of a CT scan.

So, if many CTs aren’t needed, why are so many being done? Some possible reasons:

Parents expect them, and make a fuss if they don’t happen. This is a perception among some doctors, and there is a grain of truth here, at least sometimes. Parents, even over the phone with me, sometimes immediately want a CT ordered when their child has had head trauma. Usually some calm explanations and reassurance dispels that, but some parents really seem to think a CT is necessary. Adding to this: doctors especially in hospitals have some of their pay dictated by patient satisfaction scores, and it can literally cost doctors money when there is an “unsatisfied customer.” Though it turns out that patient satisfaction is not necessarily a reliable indicator of good health or good medicine, it’s increasingly part of the way doctors are judged and paid.

They’re quick and easy. Emergency physicians are also rated on “turnover”—how quickly they can get people through the emergency department, either admitted upstairs or sent out the door. Many of the head trauma protocols suggest a period of observation as a safe and effective way to identify children at risk for serious injury. But that takes time and space and nursing resources. It’s quicker to just get the scan.

Defensive medicine. There are no guarantees; even if a child has all of the “low risk” characteristics of head trauma that should not require a CT scan, there’s probably a 1 in 10,000 risk that there really might be something wrong. Maybe it’s entirely bad luck—maybe a brain tumor that has nothing to do with trauma. But in any case, if not doing a CT scan delays a diagnosis, even a very unlikely one, doctors feel it will expose them to a risk of a lawsuit. Who needs that? Quicker to get the scan than even think about this.

The risks of cancer from a scan is way in the future. CT scans certainly do increase the lifetime risk of cancer, but only by a small percentage—and the cancer is going to happen many, many years from now. There won’t be any lawsuit, because there is never a way to prove which people with cancer got it because of exactly which medical study. That would be like figuring out which piece of candy caused a specific cavity. The risk is real, but since it’s far away and vague, it’s easy to ignore or minimize.

No one really cares about the cost. Besides a risk of cancer, are there other downsides to getting a CT scan? Yes. One is cost—excess CTs are driving up the cost of health care, and someone is paying for them. But many people feel that it isn’t them, themselves, paying. We have our insurance, we pay our copay or deductible, and who cares what the cost is? Someone ought to, everyone thinks. Just not me.

Another risk of CTs, beyond cancer and cost, is the “incidentaloma.” That’s a made-up word that refers to something unexpected found on a test that has nothing to do with the reason the test was ordered, but nonetheless makes people worry. In other words, a scan with a very low risk of finding something important and useful may still find something. About 4% of head CT scans in children are abnormal in some way. Most of those “abnormal” findings end up meaning nothing, but they still lead to anxiety and further medical workups, including, you guessed it—more CT scans.

By the way: medical people do not call these things CAT scans. They don’t involve cats. Unless, I suppose, a vet does a CT on a cat. Then that would indeed be a cat scan. Otherwise, CT is short for Computed Tomagraphy, and no “a” is necessary for abbreviation.

Coming up, a more-specific guide to CT scans: which children with head trauma really need one?

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One Comment on “Why are so many CT scans being done?”

  1. karmicventures Says:

    Reblogged this on Radiology Search.


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