Thursday, February 2, 2017

New article on imaging for kidney stones

Kevan M. Sternberg, MD, Assistant Professor of Urology and Benjamin Littenberg, MD, Professor of Medicine recently published an original research paper in the Journal of Urology. This paper came out of the work Kevan did in the UVM Medical Group course on “Introduction to clinical research using existing data.” Special thanks to instructors Charles D, MacLean, MDCM, Professor of Medicine and Associate Dean for Primary Care, Abigail Crocker, PhD, Assistant Professor of Mathematics and Statistics, Valerie Harder, MHS, PhD, Assistant Professor of Pediatrics and Psychiatry, Thomas Ahearn, PhD, Assistant Professor of Surgery.



Recent reports support the use of renal ultrasonography (US) as the initial imaging study for the evaluation of patients with suspected renal colic. Urologists, however, often advocate for computed tomography (CT) to better define stone size and location, especially prior to proceeding with endourologic intervention. One concern with using US as the initial imaging study is that CT may be required at a later time, obviating the reduction in costs and radiation gained by using US.

Materials and Methods

Retrospective review of electronic health records of 10,680 episodes of stone disease in 7,659 patients who presented to the emergency department or walk-in-clinic with a chief complaint or visit diagnosis of urolithiasis from 2009-2015 at a single institution. Images obtained during the index encounter and in the following 90 days were recorded.


The index encounter included CT in 47% of episodes, US in 20%, KUB in 12%, and no imaging in 29%. 49% of index visits included multiple testing. If no CT was obtained during the index visit, 10% received one later in the episode. Total imaging costs and radiation exposure over 90 days were significantly higher when CT was utilized during the index visit. If the initial image obtained during an episode was an US, 20% obtained a CT within 90 days.


Patients who received an initial US avoided CT imaging in 80% of the cases. Avoiding the use of CT at the index visit was associated with substantial reductions in radiation exposure and imaging cost.

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