Comparison Between Intravenous Urography and Computed Tomography Urography in Diagnosing Ureteropelvic Junction Obstruction

Ureteropelvic junction obstruction (UPJO) is mostly a benign, congenital condition that remains an enigma in terms of diagnosis. Despite several advances in morphological and functional imaging of UPJO, controversies still remain about the optimal imaging method to diagnose UPJO. Intravenous urography (IVU) has been standardized and is a familiar technique to urologists, however, its diagnostic efficacy is not high and thus another examination is usually needed. The aim of this study was to compare CTU and IVU in the assessment of patients with UPJO.Patients and Sixty-one patients with final diagnosis of UPJO received both IVU and CTU before operation. The CTU examination included three phase axial scan: noncontrast (phase I), nephrographic phase (phase II), excretory phase (phase III) and CTU images were obtained by coronal reconstruction of phase I and III. Two radiologists who were unaware of the findings independently interpreted these examinations. The diagnosis of both imaging studies were compared with the final diagnosis and the two examinations were compared by the results of diagnostic accuracy for different causes of disease. In our study, the cause of UPJO were mainly crossing vessel, stone disease, carcinoma, fiber cord compression, congenital distorted uretero-pelvic junction, inflammatory stenosis, high ureteropelvic junction, ureteral valves and renal duplication combined with obstruction. The diagnostic accuracy is 85.2% in CTU and 49.2% in IVU. Although suspicious abnormal findings in IVU were recognized in many patients (23/61), they were usually inadequate for making accurate diagnosis and further examinations were thus acquired. As compared with IVU, the operative procedure of CTU was simpler and the examination time was shorter, however, the cost and the radiation exposure was larger. CTU has higher diagnostic efficacy as compared with IVU and could be the one-stop examination for patient with UPJO. It should be under consideration to have CTU as the first line diagnostic tool, although more delicate cost-effectiveness evaluation is needed for conclusion.