Pediatric Renal Trauma

Etiology: Blunt abdominal trauma
Imaging:
— Spectrum is minor – contusion and laceration (85%) or major – laceration through collecting system (10%) or catastrophic – vascular disruption or laceration with extravasation of contrast (5%)
— Hematoma can extend into subscapsular or perirenal or anterior pararenal or peritoneal spaces
— Extravasation of urine with urinoma on delayed images
Imaging CT: Renal contusion is region of decreased parenchymal enhancement
Note:
— In renal laceration delayed post contrast imaging is needed to determine if perinephric collection represents urine leak from vascular injury or hematoma
— Prone or decubitus imaging can help determine if a leak or obstruction is present in the setting of a dilated collecting system
Note: American Association for the Surgery of Trauma (AAST) Injury Scoring Scale used to grade injury in order to help determine prognosis
DDX:
Complications: Urine leak
Treatment: Usually conservative
Clinical: Hematuria and if gross hematuria and minor trauma suspect underlying congenital renal anomaly or renal tumor

Radiology Cases of Renal Trauma

Radiology Cases of Incorrect CT Technique Without the Use of Intravenous Contrast for the Assessment of Blunt Abdominal Trauma

CT without intravenous contrast using incorrect technique for the assessment of blunt abdominal trauma — Axial CT without contrast of the abdomen shows grossly unremarkable unenhanced solid organs of the abdomen without free air or free fluid.

Radiology Cases of Renal Trauma

CT of renal laceration and suspected ureter transection — Axial CT with contrast of the abdomen (above left) shows an extensive laceration of the left kidney with an associated low density retroperitoneal hematoma surrounding the left kidney. Delayed lower axial image from the same CT exam (below left) shows extravasation of high density IV contrast around the left psoas muscle. 3D CT urogram performed the next day (right) again shows massive extravasation of IV contrast medial to the left kidney with non-visualization of the left ureter suggesting ureteral transection. The right kidney and ureter are normal. However, a retrograde urogram performed the next day showed the left ureter was not transected which allowed placement of a left ureteral stent.

CT of renal trauma / renal laceration and ureteral trauma / ureteral transection and splenic trauma / splenic laceration — Axial and coronal CT with contrast of the abdomen immediate phase (above) shows low density in the superior and inferior poles of the left kidney and fluid in the left perirenal and pararenal spaces. There is also a large area of low density in the spleen. Delayed phase CT images (below) show extravasation of urine out of the ureter into the left pararenal space.

CT of adrenal hemorrhage — Axial CT with contrast of the abdomen show a low density fluid collection in the right adrenal gland and low density in the posterior aspect of the right kidney.

CT of renal trauma / renal laceration — Axial CT with contrast of the abdomen shows areas of low density in the anterior and lateral aspects of the left kidney with associated left perirenal and pararenal high density fluid collections.

CT of renal laceration — Axial CT with contrast of the abdomen shows a laceration in the posterior aspect of the left kidney. There is isodense fluid in the left perirenal and pararenal spaces.

Radiology Cases of Renal Trauma Associated With Ureteropelvic Junction Obstruction

CT of hemorrhage into ureteropelvic junction obstruction after trauma — Coronal (above left) and sagittal (above right) CT with contrast of the abdomen show an extremely dilated right renal collecting system surrounded by an extremely thin rim of renal cortex. The axial image (below) shows high density material within the medial aspect of the renal collecting system.

CT of perirenal hematoma in a patient with a ureteropelvic junction obstruction — Axial CT without contrast of the abdomen (above) shows the unenhanced right kidney to have a low density dilated central collecting system and to be surrounded by a high density cresenteric fluid collection in the right perirenal space. Axial CT with contrast (below) better shows the low density dilated central collecting system and a decreased amount of enhancement in the right kidney when compared to the normal left kidney. The amount of enhancement in the right kidney is the same density as the right perirenal fluid collection.