Native spiral computed tomography in patients with acute flank pain - yes or no?

Purpose: To compare the diagnostic efficacy and costs of native spiral-CT and intravenous urography (IVU) in the management of patients with acute flank pain. Method: Native spiral-CT und IVU (following about 30 minutes after CT) were compared in 66 patients with acute flank pain followed by an IVU. The spiral-CT protocol was: 5-mm section thickness, 7.5-mm table feed and 3-mm increment. The analysis conducted independently by two radiologists entailed: (a) Morphology: presence of stone disease (yes-no), localization and size of calculi, periureteral and perirenal stranding, dilatation of the collecting system, and possible alternative diagnoses and (b) cost-effectiveness: direct and indirect costs. Results: Fifty-two patients had urolithiasis. The detection rate of renal and ureteric calculi was significantly higher with native spiral-CT than with IVU (100% vs. 69%, respectively) (p<0.05). A specific sign of ureteric calculi was the so-called soft tissue 'rim sign' (sensitivity 82% and specificity 100%, respectively). In 13 of 14 patients with acute flank pain with no evidence of urolithiasis alternative diagnoses could be made by spiral-CT. Spiral-CT was significantly more cost-effective than IVU in management. Conclusion: Native spiral-CT is faster, more effective and less expensive than IVU in the management of patients with acute flank pain. Additionally, it poses less risk and has the capability for allowing alternative diagnoses. Therefore, unenhanced spiral-CT should be the first line modality in patients with acute flank pain. (orig.)