Renal trauma in occult ureteropelvic junction obstruction: CT findings

The aim of this study was to present CT findings of occult ureteropelvic ju nction obstruction in patients with renal trauma and to describe the clinic al signs and singular CT features that are characteristically observed with trauma and are relevant to management of these patients. We retrospectivel y reviewed 82 helical CT studies in patients with renal trauma referred to our institution. We found 13 cases of occult preexisting renal pathology, s ix of which, were occult ureteropelvic junction obstructions. The clinical presentation, radiologic findings of trauma according to the Federle classi fication, and CT findings of obstructed ureteropelvic junction are presente d. We found three category-I lesions (one in a horseshoe kidney), two of th em treated with nephrostomy because of increased ureteropelvic junction obs truction due to pelvic clots; two category-II lesions (parenchymal and rena l pelvis lacerations) that had presented only with microhematuria; and one category-IV lesion (pelvic laceration alone). Pelvic extension was demonstr ated in all the cases with perirenal collections. The CT studies in all the cases with suspected uretero-pelvic junction obstruction showed decreased parenchymal thickness and enhancement, and dilatation of the renal pelvis a nd calyx, with a normal ureter. Computed tomography can provide information to confidently diagnose underlying ureteropelvic junction obstruction in r enal trauma, categorize the traumatic injury (at times clinically silent) a nd facilitate proper management according to the singularities observed, su ch us rupture of the renal pelvis alone (Federle category IV) and increasin g ureteropelvic obstruction due to clots which can be decompressed by nephr ostomy.