Renal trauma

Background
(1) Human urinary system: (2) kidney; (3) renal pelvis; (4) ureter; (5) urinary bladder (6) urethra.
Additional structures: (7) adrenal gland; (8) renal artery and vein; (9) inferior vena cava; (10) abdominal aorta; (11) common iliac artery and vein; (12) liver; (13) large intestine; (14) pelvis.
Renal anatomy.
Perinephric space with exaggerated pararenal space to show retroperitoneal structures. Perinephric bridging septa are seen between the left kidney and the adjacent renal fascia.
  • Approximately 10% of blunt injuries include renal trauma
  • Blunt mechanism 9x more common than penetrating[1]

Clinical Features
  • Flank pain
  • Hematuria (gross or microscopic)
  • Page kidney (late finding) - hypertension resulting from long-standing compression of from renal parenchyma by subcapsular hematoma

Differential Diagnosis

Abdominal Trauma

Evaluation
Delayed-phase CT shows fluid filling the right perinephric space in a patient following blunt trauma. The kidney has been lacerated (short arrow), and urinary contrast extravasation is shown posteriorly (long arrow)

Workup
  • CT with contrast

AAST Renal Injury Scale
Grade Description Image CT Example
I
  • Contusion
    • Microscopic or gross hematuria. Urological studies normal.
  • Hematoma
    • Subcapsular, non-expanding without parenchymal laceration.

II
  • Hematoma
    • Non-expanding peri-renal hematoma confined to renal retroperitoneum.
  • Laceration
    • <1.0 cm parenchymal depth of renal cortex without urinary extravasation.

III
  • Laceration
    • >1.0 cm parenchymal depth of renal cortex without collecting system rupture or urinary extravasation.

IV
  • Laceration
    • Parenchymal laceration extending through renal cortex, medulla, and collecting system.
  • Vascular
    • Main renal artery or vein injury with contained hemorrhage.

V
  • Laceration
    • Completely shattered kidney.
  • Vascular
    • Avulsion of renal hilum that devascularises kidney.

Management
  • Based on grade of injury (above)
  • Grade I and II
    • observation, vital signs monitoring, bed rest, antibiotic prophylaxis, monitor hematuria
  • Prophylactic IV antibiotics for grade IV, V injuries (first generation cephalosporin, ciprofloxacin, or ampicillin and gentamicin)
  • Absolute indications for operative renal exploration and intervention:
    • Life-threatening hemorrhage
    • Expanding, pulsatile, or non-contained retroperitoneal hematoma
    • Renal avulsion injury
  • Page kidney treatment involves ACE inhibitor and possible drainage of hematoma

Disposition

Admit
  • Penetrating renal injuries
  • Gross hematuria
  • Grade II or higher injury

Discharge
  • Microscopic hematuria and no indication for imaging
  • Isolated renal trauma with Grade I injury
    • Ensure close followup and instruct no heavy lifting

See Also

References
  1. Miller, K. S. and McAninch, J. W. (1995) ‘Radiographic Assessment of Renal Trauma’, The Journal of Urology, pp. 352–355.
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