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Figure 1b.   Urine extravasation from the collecting system in a 9-year-old boy who had sustained blunt abdominal trauma. (a) Contrast-enhanced generalized-nephrographic-phase helical CT scan reveals what appears to be only a large perinephric hematoma (H) secondary to a distinct renal laceration (not shown). Because this is an early-phase image, there is no contrast material in the collecting system. The descending colon (C) is displaced anteriorly by the hematoma. Note the thickening of the renal (arrow) and lateroconal (arrowhead) fascia. (b) Excretory-phase CT scan demonstrates extensive extravasation of contrast-enhanced urine admixed with the hematoma, a finding that demonstrates that the laceration has disrupted the integrity of the collecting system.