US as Good as CT in the Diagnosis of Nephrolithiasis

Smith-Bindman et al report in the NEJM the results of a three-year trial on 2,759 adults who presented in 15 emergency departments with symptoms of nephrolithiasis. The patients were randomly assigned to undergo initial diagnostic ultrasonography performed by an emergency physician (point-of-care ultrasonography), ultrasonography performed by a radiologist (radiology ultrasonography), or abdominal CT.

Physicians in the ED performed ultrasonography in 908 patients, while radiologists performed ultrasonography in 893 patients, and 958 patients had CT. The incidence of high-risk diagnoses with complications in the first 30 days was low (0.4%) and did not vary according to imaging method. The mean 6-month cumulative radiation exposure was significantly lower in the ultrasonography groups than in the CT group (P<0.001). Serious adverse events occurred in 12.4% of the patients assigned to point-of-care ultrasonography, 10.8% of those assigned to radiology ultrasonography, and 11.2% of those assigned to CT (P=0.50). Related adverse events were infrequent (incidence, 0.4%) and similar across groups. By 7 days, the average pain score was 2.0 in each group (P=0.84). Return visits to emergency department, hospitalizations, and diagnostic accuracy did not differ significantly among the groups.

The authors concluded that no significant differences were found in diagnostic accuracy, serious adverse events, pain scores, return visits to the emergency department, or hospitalizations when ultrasound was used instead of CT.   Ultrasonography was associated with lower cumulative radiation exposure than CT, and is less expensive therefore it may become the study of choice in the diagnosis of nephrolithiasis in the ED department.