URETERAL CALCULI IN PATIENTS WITH FLANK PAIN - CORRELATION OF PLAIN RADIOGRAPHY WITH UNENHANCED HELICAL CT

PURPOSE: To determine the sensitivity and specificity of plain radiogr aphy for the detection of ureteral calculi with use of unenhanced heli cal computed tomography (CT) as the standard of reference. MATERIALS A ND METHODS: Plain radiographs and helical CT scans of 178 patients wit h acute flank pain were reviewed retrospectively. Three interpretation s of plain radiographs were used: (a) Original reading. This was the r eport made at the time of the patient's evaluation before the patient underwent CT. (b) Blinded retrospective reading. Each plain radiograph was interpreted without knowledge of the CT findings. (c) Unblinded r etrospective reading. The plain radiograph of each patient whose CT sc an showed a stone was reviewed with the CT scan. RESULTS: The original reading had a sensitivity of 45% and a specificity of 77% for the det ection of ureteral calculi. The blinded retrospective reading had a se nsitivity of 59% and a specificity of 71%. The unblinded retrospective reading had a sensitivity of 59% (95% confidence interval: 47%, 70%). CONCLUSION: Plain radiography is of limited value for aiding the diag nosis of ureteral stones. All patients with acute flank pain for whom radiologic imaging is recommended can directly undergo unenhanced heli cal CT; plain radiographs need not be obtained first.