Prospective Comparison of Unenhanced Spiral Computed Tomography and Intravenous Urography in the Evaluation of Acute Renal Colic

Background: The purpose of this prospective study was to evaluate the feasibility of replacing intravenous urography (IVU) with unenhanced computed tomography (CT) as the first line diagnostic modality for acute renal colic in the emergency department. Methods: In the 1-year study period, 82 patients who presented themselves to the emergency room with acute renal colic and who were suspected to have ureteral stones were included. They received both IVU and unenhanced CT on the same day. Results: Sixty-six patients were proven to have ureteral stone. Four had other urologic pathology (acute pyelonephritis, angiomyolipoma with hemorrhage, ureteropelvic junction stenosis). The remaining 12 had no definite urologic problem. Among the 66 patients with ureteral stone, the sensitivity for detecting ureteral stone was 98.5% for unenhanced CT and 59.1% for IVU. Correct diagnosis could be obtained in most of the patients receiving unenhanced CT, while IVU could provide only limited information about the intra-abdominal pathology other than urologic system, and as many as 31.7% of the patients needed further imaging examination (sonography, CT, magnetic resonance imaging). In 5 patients, the relationship of the calcified spot and ureter were unclear on axial images. With curved multiplanar reformatted reconstruction, the diagnosis of ureter stone could be confidently made. No side effect (renal toxicity, allergic reaction) from intravenous administration of iodine-containing contrast medium should be taken into consideration in CT. Besides, the average examination time was 108 minutes for IVU, which was significantly more than the 30 minutes for CT, including the time for curved multiplanar reformatted reconstruction. Conclusion: We consider that unenhanced CT is more effective and efficient than IVU and should replace IVU as the first-line diagnostic tool for ureteral stone in the emergency department.