A blunt renal trauma case with delayed urinary extravasation

To diagnose traumatic urinary extravasation, reexamination within 48 hours after initial excretory-phase computed tomography (CT) is recommended. We report a case of delayed traumatic urinary extravasation that was not detected on CT twice within 48 hours after injury. The patient was a 42-year-old female with blunt right renal injury. Initial CT showed a complex deep injury of the right lower kidney, no urinary extravasation, partial residual contrast medium in the injured renal parenchyma, and arterial extravasation that was not depicted on angiography. On the next day, excre-tory-phase CT images showed no urinary extravasation and partial residual contrast medium, and truncation of the right lower calyces was detected on maximum intensity projection (MIP) images. On the 8th day after injury, excreto-ry-phase CT images depicted urinary extravasation at the right lower kidney and disappearance of partial residual contrast medium. On MIP images, urinary extravasation was detected at the right lower calyces. Urinary extravasation spontaneously disappeared on the 21st day after injury. In this patient, obstruction of injured calyces was regarded as the cause of delayed excretion of contrast medium in the injured renal parenchyma and delayed urinary extravasation. MIP images were useful to detect calyceal obstruction and to diagnose delayed urinary extravasation.