National Imaging Trends for Suspected Urinary Stone Disease in the Emergency Department

Flank pain from urinary stone disease (USD) is a common presentation to the emergency department (ED) in the US.¹ The American Urological Association (AUA) currently recommends computed tomography (CT) as the preferred initial imaging study for suspected USD,² and CT has become the dominant imaging modality used for this purpose in the ED.¹ In 2014, Smith-Bindman et al³ reported results from a multicenter randomized clinical trial comparing ultrasonography with CT in patients who presented to the ED with suspected USD and showed that an ultrasonography-first strategy was not associated with more serious adverse events, missed high-risk diagnoses, or delays in urologic procedures. The ultrasonography-first strategy also has the potential advantage of exposing patients to lower cumulative doses of radiation. There is now consensus among representatives from the American College of Emergency Physicians, American College of Radiology, and AUA that supports ultrasonography for the initial evaluation of suspected uncomplicated USD.⁴ More recent studies have yet to determine whether practice patterns have changed.

We used data from the Nationwide Emergency Department Sample from January 2012 to December 2018. Per Stanford institutional review board guidelines, this project did not meet the definition of human participants research because we did not receive or have access to individually identifiable information. Informed consent was waived owing to the use of deidentified data. We selected patients 18 years or older who presented to the ED with suspected USD according to International Classification of Diseases, Ninth Revision (ICD-9) and ICD-10 codes. We excluded patients who were pregnant and those with end-stage kidney disease. We used Current Procedural Terminology codes from the ED visits and ICD-9 and ICD-10 procedure codes to assess the imaging modality for each patient. We analyzed trends of ED visits with no imaging, CT alone, ultrasonography alone, or CT and ultrasonography.

We identified 7 549 046 unique ED visits for suspected USD between 2012 and 2018. We chose alternating years between 2012 and 2018 as representative years (Table). Patients were similar in age (mean [SD] age, 45.0 [0.12] years in 2012 and 46.3 (0.12) years in 2018) and sex distribution (40.1% female in 2012; 42.1% in 2018). Most ED visits for suspected USD were followed by routine discharge from the ED (88.9% in 2012; 96.0% in 2018). The proportion of visits with no imaging study decreased from 50.5% in 2012 to 39.1% in 2018. While visits with ultrasonography increased from 1.49% in 2012 to 2.07% in 2018, visits with CT increased from 48.6% in 2012 to 59.2% in 2018 (Figure). These imaging trends were similar for men and women, teaching hospital status (teaching or nonteaching hospital), and payer type (private insurance, Medicare, or Medicaid).

The results of this cohort study suggest that as of 2018, fewer than 3% of annual ED visits for suspected USD included ultrasonography, whereas more than 50% of annual ED visits included CT. One limitation of this analysis is that we identified the imaging modality associated with an eventual diagnosis of USD, which may not always reflect the choice of imaging modality made by clinicians while they were evaluating symptoms preceding a diagnosis of USD. Even so, CT is the dominant imaging tool being used in ED visits associated with USD. Ultrasonography may be preferable to CT for the following reasons: (1) to our knowledge, no studies have documented the superiority of CT in improving USD outcomes or in reducing morbidity³; (2) although CT is highly sensitive for stone detection, the superior sensitivity of CT may not matter for smaller stones that pass without intervention; (3) use of point-of-care ultrasonography may be associated with shorter wait times in the ED; and (4) use of ultrasonography limits the exposure of patients with recurrent stone events to repetitive doses of ionizing radiation.⁵

These imaging trends should encourage the AUA to follow the lead of the European Urological Association and update guidelines that recommend ultrasonography for the initial evaluation of suspected USD.⁶ Greater awareness of evidence and updated guidelines may increase adoption of an ultrasonography-first strategy. These changes may reduce radiation exposure to patients and limit health care costs.

Accepted for Publication: July 15, 2022.

Published Online: October 31, 2022. doi:10.1001/jamainternmed.2022.4939

Corresponding Author: Calyani Ganesan, MD, Division of Nephrology, Department of Medicine, Stanford University, 3180 Porter Dr, Room B220, Palo Alto, CA 94304 (calyani@stanford.edu).

Author Contributions: Mr Liu had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Drs Leppert and Pao had equal senior authorship.

Concept and design: Ganesan, Conti, Leppert, Pao.

Acquisition, analysis, or interpretation of data: Ganesan, Stedman, Liu, Chertow, Pao.

Drafting of the manuscript: Ganesan, Stedman, Conti, Leppert, Pao.

Critical revision of the manuscript for important intellectual content: Ganesan, Liu, Conti, Chertow, Leppert, Pao.

Statistical analysis: Ganesan, Stedman, Liu, Pao.

Obtained funding: Leppert, Pao.

Administrative, technical, or material support: Conti, Chertow, Leppert, Pao.

Supervision: Chertow, Leppert, Pao.

Conflict of Interest Disclosures: Dr Chertow reported personal fees from Satellite Healthcare, Akebia, Gilead, Goldfinch Bio, Reata, Sanifit, Vertex, Bayer, Mineralys, Palladio, and ReCor; advisory board service, stock options, and personal fees from AstraZeneca and Cricket; advisory board service for CloudCath and DiaMedica; and stock options from Durect, Eliaz Therapeutics, Miromatrix, and Outset outside the submitted work. No other disclosures were reported.