Renal Injury

Basics

Description

  • Kidneys are located in the retroperitoneal space:
    • Protected by the lower ribs, back musculature, and perinephric fat
  • At level of lower 2 thoracic vertebrae and 1st 4 lumbar vertebrae
  • Left kidney higher than the right due to the liver
  • Kidneys are not fixed:
    • Shift with the diaphragm and supported by the renal arteries, veins, and (Gerota) fascia

Etiology

  • Most common of all urologic injuries
  • Occurs in ∼8–10% of all abdominal trauma
  • Blunt renal trauma (80–85%) of all renal injuries and is 5 times more common than penetrating injury:
    • Mechanisms include motor vehicle accidents, falls, domestic violence, and contact sports
    • From rapid deceleration/displacement mechanisms a/w intraperitoneal injury (20%)
  • Renal trauma injury commonly associated with other vital organs that can be responsible for patient mortality
  • Renal injuries are graded by type and severity of injury (AAST) criteria:
    • Grade I:
      • Contusion: Microscopic or gross hematuria, urologic studies normal
      • Hematoma: Subcapsular, nonexpanding w/o parenchymal laceration
    • Grade II:
      • Hematoma: Nonexpanding, perirenal hematoma confined to retroperitoneum
      • Laceration: <1-cm parenchymal depth to cortex w/o urinary extravasation
    • Grade III:
      • Laceration: >1-cm parenchymal depth to cortex w/o collecting system rupture or urinary extravasation
    • Grade IV:
      • Laceration: Parenchymal laceration extending through renal cortex, medulla, and collecting system
      • Vascular: Main renal artery or vein injury with contained hemorrhage
    • Grade V:
      • Laceration: Completely shattered kidney
      • Vascular: Avulsion of renal hilum, devascularizing the kidney

Pediatric Considerations

  • The kidney most commonly damaged by blunt abdominal trauma:
  • Bicycle accidents common mechanism Contributing factors:
    • Relatively larger size of kidneys compared with adults
    • 10th and 11th ribs not completely ossified until 3rd decade of life
  • Significant abdominal injury occurs in about 5% of nonaccidental trauma cases
  • 2nd most common cause of death after head injury
  • May not manifest hypotension with renal injury like adults

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