National Imaging Trends in Nephrolithiasis-Does Renal Ultrasound in the Emergency Department Pave the Way for...

Concern regarding radiation exposure has led to increased interest in the use of ultrasound for the initial imaging of suspected renal colic in the emergency department. It is unknown whether such an approach simply defers computerized tomography to outpatient followup. We analyzed national imaging patterns to explore this relationship.

Using the MarketScan® insurance claims database we reviewed adult patients newly diagnosed with nephrolithiasis in U.S. emergency departments between 2007 and 2015. Patients were excluded if they had been diagnosed with or undergone treatment for nephrolithiasis in the preceding 180 days.

From 2007 to 2015, 830,785 emergency department nephrolithiasis encounters met inclusion criteria. The ultrasound-only rate increased from 2.7% to 6.9%, while the computerized tomography-only rate remained stable at 85.8%. A history of computerized tomography in the 30 days before emergency department presentation increased the rate of ultrasound-only imaging from 4.6% to 8.9%. The mean cumulative computerized tomography scans from the emergency department visit to 90 days after was significantly lower in those imaged with emergency department ultrasound (0.82±0.77) compared to those imaged with emergency department computerized tomography (1.2±0.51, p <0.001).

Patients who undergo ultrasonography in the emergency department for evaluation of renal colic undergo fewer cumulative computerized tomography scans in the 90 days following their visit than do patients initially imaged with computerized tomography. Ultrasound use for the evaluation of renal colic has increased while computerized tomography rates have remained stable.