The following article features coverage from the American Urological Association (AUA) 2019 meeting. Click here to read more of Renal & Urology News’ conference coverage.

CHICAGO—Computed tomography (CT) alone is used in the vast majority of diagnostic imaging studies for suspected kidney stones in emergency department (ED) visits in the United States, investigators reported at the 2019 American Urological Association annual meeting.1

The finding suggests substantial potential for reducing patient radiation exposure during ED visits for nephrolithiasis by using ultrasound (US) scans instead, according to Diana K. Bowen, MD, of Northwestern University Feinberg School of Medicine in Chicago, and colleagues at The Children’s Hospital of Philadelphia. A previous randomized study published in The New England Journal of Medicine2 found that use of US as the first diagnostic imaging study for adults with suspected ureteral stones decreased radiation exposure without increasing the likelihood of return ED visits or missed diagnoses, the authors noted. Guidelines from the European Association of Urology recommend that US should be the first imaging modality for suspected nephrolithiasis.

Dr Bowen’s team conducted a cross-sectional study of adults who presented to 70 EDs in South Carolina from 1996 to 2017 using all-payer hospital claims data. Patients had a mean age of 44 years. Women made up 36.7% of the study population. They identified all ED encounters within a 6-month period following a kidney stone diagnosis.

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The study population included 180,845 patients with 233,242 unique stone episodes involving at least 1 ED visit and 282,845 ED encounters. A CT scan was obtained in 72.8% of all ED encounters compared with only 3.5% with US. CT scans were obtained without US in 94.8% of all ED visits during which US scans and/or CT scans were obtained. Of those stone episodes that involved at least 2 consecutive ED visits, 79.1% represented an opportunity for reduction in CT use, Dr. Bowen and her colleagues reported.

In addition, 28% of patients presented to different EDs for the initial and subsequent visits, and CT use patterns between those who presented to the same ED and different EDs were similar (90% vs 93.9%).

“An US-first approach offers substantial potential for radiation reduction during ED visits for nephrolithiasis,” the authors concluded.

Read more of Renal & Urology News’ coverage of the AUA 2019 meeting by visiting the conference page.


  1. Bowen DK, Song L, Tasian GE. Patterns of CT and US utilization for nephrolithiasis in the emergency department. Presented at the 2019 American Urological Association annual meeting held May 3-6 in Chicago. Abstract MP08-02
  2. Smith-Bindman R, Aubin C, Bailitz J, et al. Ultrasonography versus computed tomography for suspected nephrolithiasis. N Engl J Med. 201;371:1100-1110.