Ultrasound-First Nephrolithiasis Evaluation for Appropriate Patients Would Reduce U.S. Costs by Millions

Non-contrast CT is still the gold standard for detecting nephrolithiasis. However, point-of-care ultrasound (POCUS) is quicker and less expensive, and a growing body of clinical literature supports considering a POCUS-first approach to nephrolithiasis evaluation.

In 2014, the Choosing Wisely committee of the American College of Emergency Physicians published a recommendation to “avoid ordering CT of the abdomen and pelvis in young otherwise healthy emergency department patients [age <50] with known histories of ureterolithiasis presenting with symptoms consistent with uncomplicated kidney stones.”

Now, researchers at Brigham and Women’s Hospital have demonstrated that a POCUS-first approach for patients who meet those criteria could produce substantial national cost savings, as well as clinical benefits. George E. Haleblian, MD, urologic surgeon in the Department of Urology, Andrew J. Goldsmith, MD, MBA, chief of Emergency Ultrasound in the Department of Emergency Medicine, Christopher Baugh, MD, MBA, and Nicole Duggan, MD, of the Department of Emergency Medicine, and colleagues report in The American Journal of Emergency Medicine.


The researchers developed a computer simulation whose main inputs were:

  • Annual number of emergency department (ED) visits for nephrolithiasis, estimated using CDC data
  • Percentage of nephrolithiasis cases in patients <50, estimated using data from the Massachusetts All Payers’ Claims Database
  • Percentage of nephrolithiasis cases with a known history of nephrolithiasis, estimated using data from a multicenter randomized controlled trial published in The NEJM
  • Percentage of cases of uncomplicated nephrolithiasis, estimated using the same source
  • Sensitivity of POCUS for detecting hydronephrosis in ED patients with suspected nephrolithiasis, estimated using data from a prospective observational study published in The Ultrasound Journal
  • Reimbursement for CT and POCUS, estimated using Medicare data

Primary Analysis

The simulation estimated that a POCUS-first approach for nephrolithiasis among patients who meet Choosing Wisely criteria would avert an average of 159,000 CT scans annually, representing an average annual cost savings of $16.5 million. Those figures assume all patients with nephrolithiasis would undergo CT at baseline under the current standard of care.

Secondary Analysis

The POCUS-first approach yielded several other benefits nationally:

  • Cumulative decrease in ED bed hours by an average of 166,000 annually
  • Reduction in radiation exposure by an average of 1.9 million person-mSv annually
  • Prevention of 232 cancer cases annually and 118 cancer deaths annually because of the decrease in radiation exposure

Sensitivity Analysis

100% adherence to Choosing Wisely guidelines is probably unrealistic, but substantial benefits would accrue even with much lower adherence. Just 20% adoption of the POCUS-first approach above the current rate would avert an estimated 32,000 CT scans annually, resulting in:

  • $3.3 million in cost savings
  • 33,000 bed-hour reduction in cumulative ED length of stay
  • 0.4 million person-mSv reduction in radiation exposure
  • 46 cancer cases prevented
  • 24 cancer deaths prevented

Rationale for the Choosing Wisely Recommendation

Patients who meet Choosing Wisely guidelines are at lower than average risk for alternative dangerous pathology that can mimic nephrolithiasis. Frequent CT scans and substantial cumulative radiation exposure are the greater hazards for them. In addition, cancer incidence/death is particularly burdensome in the younger adult population.

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