CT or ultrasound, which is better for kidney stone diagnosis? Study provides insights

"Computed tomography is the dominant imaging tool in the ED for evaluating and diagnosing kidney stones, but it may not be the best," Calyani Ganesan, Stanford University, Palo Alto, California, and colleagues wrote in their study.

Flank pain due to urinary stone disease (USD) is a common presentation in the ED in the US. The American Urological Association recommends CT as the favorable initial imaging study for suspected USD. For this purpose, CT has become the dominant imaging modality used in the ED.

Smith-Bindman et al., in 2014, reported results from a multicenter randomized clinical trial comparing ultrasound with CT in patients presenting to the ED with suspected USD and showed that the first strategy of ultrasonography was not tied to more serious adverse events, delays in urologic procedures, or missed high-risk diagnoses. Also, the ultrasonography-first approach has the potential advantage that it exposes patients to lower cumulative radiation doses. Now, there is consensus among representatives from the American College of Radiology, AUA, and the American College of Emergency Physicians that supports ultrasonography for the initial evaluation of suspected uncomplicated USD. Whether practice patterns have changed needs to be determined by more recent studies.

Ganesan and the research team aimed to explore imaging trends for suspected urinary stone disease through a study that included data from the Nationwide Emergency Department Sample. They compared ED visits during which patients did not have imaging to those during which patients underwent CT alone or ultrasound alone. The patient cohort comprised 7.5 million unique ED visits for suspected kidney stones.

The study demonstrated the following findings:

· During the study time frame, the percentage of visits to the emergency department for a suspected urinary stone disease that did not include any imaging fell.

· The percentage of visits during which patients underwent CT increased by more than 50%, while the use of ultrasound increased only slightly.

More research needs to be done to shift the proverbial need among ED physicians when using ultrasonography rather than CT for kidney stone diagnosis.

The researchers conclude, "updated guidelines and greater awareness of evidence may increase adoption of an ultrasonography-first strategy. These changes may decrease radiation exposure to patients and limit health care costs."

Reference:

Ganesan C, Stedman MR, Liu S, et al. National Imaging Trends for Suspected Urinary Stone Disease in the Emergency Department. JAMA Intern Med. Published online October 31, 2022. doi:10.1001/jamainternmed.2022.4939