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Ultrasound or CT for Nephrolithiasis

December 30, 2017

On the Shoulders of Giants

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An ultrasound-first strategy, especially for recurrent kidney stones, was a good way to reduce radiation exposure in patients presenting to the ED with renal colic.

Why does this matter?
Many patients with kidney stones undergo multiple CT scans, which each require large radiation doses.  Would it be safe to start with an ultrasound vs. a CT in such patients?

Stones, loans, scones, and psychedelic overtones
Adult patients with suspected kidney stone were randomized to an ultrasound-first or CT-first imaging strategy, with subsequent management or imaging per physician discretion, to determine 30-day risk of complications and 6- month cumulative radiation exposure.  Almost 2800 patients were randomized to ED physician ultrasound, radiology ultrasound, or CT first.  Complication rates were rare and the same in all groups. Cumulative 6-month radiation exposure was lower in the ultrasound-first groups. Average reduction was 7.5 mSv, which is the equivalent of at least 75 chest x-rays.  Limitations – It was unblinded. Also, ED point-of-care ultrasound was done by emergency physicians trained to do the studies, which may not be the case in all EDs.  Overall, starting with ultrasound in patients with suspected kidney stones was a good way to reduce radiation exposure without causing harm.

Ultrasonography versus computed tomography for suspected nephrolithiasis.  N Engl J Med. 2014 Sep 18;371(12):1100-10. doi: 10.1056/NEJMoa1404446.

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What are your thoughts?