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

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

• Abdominal compartment syndrome
• Diaphragmatic trauma
• Duodenal hematoma
• Genitourinary trauma
• Liver trauma
• Pelvic fractures
  • Acetabular pelvic fractures
  • Open book pelvic fracture
  • Straddle pelvic fracture
  • Pelvic avulsion fracture
• Retroperitoneal hemorrhage
• Renal trauma
• Splenic trauma
• Trauma in pregnancy
• Ureter trauma

Evaluation

thumb|Abdominal trauma resulting in a right kidney contusion (open arrow) and blood surrounding the kidney (closed arrow) as seen on CT.

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

Diagnosis

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

• GU Trauma