Urolithiasis in patients with acute flank pain: Comparison of plain abdominal radiography to unenhanced spiral CT

The unenhanced spiral CT has been used to evaluate patients with acute flank pain popularly in the United States for many years. We performed this study to reassess the value and limitation of the plain KUB film in comparison with the unenhanced spiral CT in 101 patients with acute flank pain. We obtained a sensitivity of 63% and 98% for diagnosing urinary stones by the plain abdominal radiography and the unenhanced spiral CT respectively. About one-third of the stones depicted by the unenhanced CT were not able to be demonstrated on the plain radiographs in our patients. In the presence of secondary signs of ureteric obstruction including ureteric dilatation, it is still possible to differentiate stones from phleboliths in pelvic cavity on the unenhanced CT. We confirm that the plain radiography is of less value in evaluation of patients with acute flank pain caused by urolithiasis in comparison with the unenhanced spiral CT. We recommend the unenhanced spiral CT as a method of choice to assess the patients with acute flank pain when the results of physical examination and plain KUB film are inconclusive or suspicions for urolithiasis, and when the IVP is contraindicated to the patient or the patient hesitate to receive such a study.