Trends in the use of unenhanced helical CT for acute urinary colic

OBJECTIVE. Unenhanced helical CT for urolithiasis detection is a limited CT examination that was designed specifically for the detection of urolithias is. The purpose of this study was to repeat a prior study to assess whether clinicians had broadened the indications and changed the yield and finding s of unenhanced helical CT. MATERIALS AND METHODS. One hundred consecutive patients with suspected rena l colic or flank pain referred for unenhanced helical CT were selected for this study. We reviewed the original radiographic reports for each patient and recorded the presence of ureteral calculi. Other urinary abnormalities and extraurinary lesions were also recorded and compared with the results o f the previous study. RESULTS. In this study, 56% of the patients who underwent unenhanced helica l CT had symptoms of urinary colic, and 44% of patients had unspecified fla nk pain, compared with 100% of patients with symptoms of urinary colic 1 ye ar earlier. The sensitivity and specificity of unenhanced helical CT in det ecting ureteral calculi were 96% and 99%, respectively. Ureteral calculi we re identified in only 28% of the patients versus 49% of patients (p < .01) 1 year earlier. Extraurinary lesions were identified in 45% of the patients versus 16% (p < .01) 1 year before. CONCLUSION. As clinicians developed familiarity with this technique, the in dications for performance of unenhanced helical CT were expanded with a con sequent reduction in the rate of detection of stone disease and identificat ion of an increased number of extraurinary lesions, which suggests a demand for emergency abdominal CT studies.