Ultrasound could replace CT scans as first test for kidney stones, lowering radiation

A national team including a Group Health researcher has found a way to make some trips to the emergency room safer and potentially less costly: Use ultrasound as the first test for kidney stones. Pain from the calcium-based crystals is a common reason for emergency room visits. One in 11 Americans says they've had at least one kidney stone in their lifetime. Usually, people suspected of having this condition are examined by CT (computed tomography), a type of X-ray imaging that delivers a great deal of ionizing radiation. A research team including Group Health Research Institute Senior Investigator Diana Miglioretti, PhD, tested whether ultrasound imaging, which doesn't use radiation, could be just as effective for this initial step.

In the study, reported in the New England Journal of Medicine, 2,759 adults visiting 15 emergency rooms across the country for suspected kidney stones were randomly chosen for one of three initial exams: CT, ultrasound from an emergency room doctor, or ultrasound from a radiologist. Up to 41 percent of patients who received ultrasound also had CT later; but for many, ultrasound was sufficient for an accurate diagnosis. Cost analyses are continuing, but when compared to CT scanning, initial imaging by ultrasound did not increase cost, patient pain, serious side effects, or return visits to the hospital.

In comments at her university, lead author Rebecca Smith-Bindman, MD, University of California San Francisco, said that emergency room doctors should consider ultrasound as a first imaging option for suspected kidney stones—and patients should ask if ultrasound instead of CT is appropriate. This work aligns with Group Health's award-winning efforts to improve medical imaging.

Dr. Miglioretti is also dean’s professor of biostatistics in the Department of Public Health Sciences, School of Medicine at the University of California Davis. Many news media, including the New York Times and Reuters, covered this study.

by Chris Tachibana