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N Engl J Med. 2014 Sep 18;371(12):1100-10. doi: 10.1056/NEJMoa1404446.

Ultrasonography versus computed tomography for suspected nephrolithiasis.

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From the Departments of Radiology and Biomedical Imaging (R.S.-B., R.B.G., M. Moghadassi), Epidemiology and Biostatistics and the Philip R. Lee Institute for Health Policy Studies (R.S.-B.), Urology (M.L.S.), Medicine (V.E.V.), and Emergency Medicine (R.C.W.), University of California, San Francisco (UCSF), and the San Francisco Coordinating Center, California Pacific Medical Center Research Institute (D.R.K., S.R.C.), San Francisco, the Department of Emergency Medicine, UCSF, Fresno (R.N.B.), Keck School of Medicine of the University of Southern California, Los Angeles (T.L.K.), Center for Healthcare Policy and Research (J.M.) and Division of Biostatistics, Department of Public Health Sciences (D.L.M.) and the Department of Emergency Medicine (L.D.M.), University of California, Davis - all in California; the Division of Emergency Medicine, Washington University School of Medicine, St. Louis (C.A., R.T.G.); Department of Emergency Medicine, John H. Stroger, Jr. Hospital of Cook County, and the Department of Emergency Medicine, Rush University Medical Center - both in Chicago (J.B.); Department of Emergency Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (C.A.C., V.E.N.); Department of Emergency Medicine, Jacobi Medical Center, Bronx, NY (J.C., J.W.); Department of Emergency Medicine, Hospital of the University of Pennsylvania, Philadelphia (A.J.D.); Rhode Island Hospital and Brown University Department of Emergency Medicine, Providence (G.D.J.); Department of Emergency Medicine, Oregon Health and Science University, Portland (O.J.M.); and Group Health Research Institute, Group Health Cooperative, Seattle (D.L.M.); University of Utah, Salt Lake City (M. Mallin); Emory University School of Medicine, Atlanta (W.M.); University of Texas Health Science Center at Houston (S.K.M.) and the University of Texas at Houston Medical School (G.M.P.) - both in Houston; and the Hennepin County Medical Center, Minneapolis (J.R.M.).



There is a lack of consensus about whether the initial imaging method for patients with suspected nephrolithiasis should be computed tomography (CT) or ultrasonography.


In this multicenter, pragmatic, comparative effectiveness trial, we randomly assigned patients 18 to 76 years of age who presented to the emergency department with suspected nephrolithiasis to undergo initial diagnostic ultrasonography performed by an emergency physician (point-of-care ultrasonography), ultrasonography performed by a radiologist (radiology ultrasonography), or abdominal CT. Subsequent management, including additional imaging, was at the discretion of the physician. We compared the three groups with respect to the 30-day incidence of high-risk diagnoses with complications that could be related to missed or delayed diagnosis and the 6-month cumulative radiation exposure. Secondary outcomes were serious adverse events, related serious adverse events (deemed attributable to study participation), pain (assessed on an 11-point visual-analogue scale, with higher scores indicating more severe pain), return emergency department visits, hospitalizations, and diagnostic accuracy.


A total of 2759 patients underwent randomization: 908 to point-of-care ultrasonography, 893 to radiology ultrasonography, and 958 to 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 emergency department visits, hospitalizations, and diagnostic accuracy did not differ significantly among the groups.


Initial ultrasonography was associated with lower cumulative radiation exposure than initial CT, without significant differences in high-risk diagnoses with complications, serious adverse events, pain scores, return emergency department visits, or hospitalizations. (Funded by the Agency for Healthcare Research and Quality.).

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