Usefulness of computed tomography performed immediately after excretory urography in patients with delayed opacification or dilated upper urinary tract of unknown cause

Abstract

To evaluate the diagnostic value of computed tomography (CT) performed immediately after excretory urography (EU) in patients with delayed renal opacification or dilated upper urinary system with nonconclusive diagnosis after EU. CT was performed immediately after EU in 39 patients with delayed opacification or dilated upper urinary system of unknown cause, without additional intravenous contrast administration for the CT study. We classified EU + CT findings as benign or malignant causes and we compared our results with the final diagnosis. The combination of EU + CT correctly diagnosed 38 out of the 39 cases with a sensitivity of 97%. Correct diagnosis was established in all malignant cases (n = 17) but one benign case consistent with blood clots in the upper urinary tract was incorrectly diagnosed as a multicentric urothelial carcinoma. Sensitivity, specificity, and accuracy for the diagnosis of the underlying cause with EU + CT was 100%, 95%, and 97%, respectively. The final diagnoses were: urothelial carcinoma (n = 10), stone disease (n = 10), bladder tumor (n = 4), benign post-treatment ureteral stenosis (n = 4), ureteral invasion (n = 3), benign bladder disease (n = 2), urinary tract infections (n = 2), crossing vessels (n = 1), ureteropelvic junction obstruction (n = 1), retrocaval ureter (n = 1), and blood clots in the upper urinary tract due to bleeding renal metastasis from lung cancer (n = 1). Combined EU and CT study allowed correct diagnosis of the underlying cause of delayed excretion or upper urinary tract dilatation in 97% of cases. The combination of EU and CT provides diagnosis reducing time and radiation.