CT scans and ultrasounds are equally effective at finding kidney stones and ultrasounds should be used as a first step to avoid unnecessary radiation exposure, US researchers said Wednesday.
The study in the New England Journal of Medicine randomized nearly 3,000 people who went to emergency rooms for suspected kidney stones.
Some underwent ultrasound by an ER doctor, others had an ultrasound from a trained specialist or were given a computed tomography (CT) scan by a radiologist.
After six months of follow up, there were no differences in health outcomes between the three groups.
Currently, CT scans are more frequently used than ultrasound when a patient presents with painful symptoms that could result from kidney stones.
The study did not urge doctors to stop doing CT scans, only to try ultrasound first and then follow up with a scan if needed.
"Ultrasound is the right place to start," said lead researcher Rebecca Smith-Bindman, professor at the University of California, San Francisco.
"Radiation exposure is avoided, without any increase in any category of adverse events, and with no increase in cost."
According to the 2010 US National Health and Nutrition Examination Survey, one in 11 people reported having had at least one kidney stone, the article said.
"The use of CT to diagnose kidney stones has risen 10-fold in the last 15 years," it added.