Subcapsular Hematoma and
Renal Laceration

General considerations

  • Incidence
    • Renal trauma is most common of all GU trauma occurring in about 10% of patients with significant blunt or penetrating abdominal trauma
  • Cause
    • Motor vehicle accident
    • Contact sports
    • Falls and fights
    • Less often penetrating wounds
  • Mechanism
    • Direct blow (>80%) frequently compressed and often lacerated by lower ribs
    • Acceleration-deceleration injuries can produce renal artery tears
  • Associated with other organ injury in 20% of cases

Clinical findings

  • More than 95%  have hematuria
    • About 25% of patients with gross hematuria have significant injuries
    • But, 24% of patients with renal pedicle injury have no hematuria
    • Only 1-2% with microhematuria have a severe renal injury

Types of injuries

CT Classification of Renal Trauma

CT Grade

Injury

Usual Treatment

Grade I

Superficial cortical laceration, contusion and/or perirenal hematoma

Observation

Grade II

Deep corticomedullary laceration involving the collecting system

Observation or surgery

Grade III

Renal crush injury and/or main vascular pedicle injury

Surgery

Grade IV

Injury of the renal pelvis or the ureteropelvic junction

Surgery

  • Renal contusion
  • Superficial cortical laceration (75-85%)
  • Small cortical laceration without calyceal disruption
  • Complete cortical laceration
    • Fracture communicating with calyceal system (10%)
      • Extraluminal contrast material
      • Separation of renal poles or fracture
  • Crush injury
    • Usually involves injury to the renal vascular pedicle (5%)
    • Multiple separate renal fragments
      • Lack of enhancement of part or all of kidney
    • Extraluminal contrast material
  • Subcapsular hematoma

Imaging Findings

  • Contrast-enhanced CT of the abdomen and pelvis is the study of choice
    • Delayed scans may be needed to detect extraluminal contrast
  • Contusion
    • Focal patchy areas of decreased enhancement
  • Renal laceration
    • Irregular linear hypodense parenchymal areas
    • They may be hyperdense if they contain blood
  • Fracture
    • Laceration connecting two cortical surfaces
  • Shattered kidney
    • Multiple separated renal fragments with or without perfusion
  • Subcapsular hematoma
    • Superficial crescentic, usually hyperdense zone beneath renal capsule and compressing adjacent parenchyma
    • Less common than perinephric hematoma
      • Perinephric hematomas presents as a poorly-defined, hyper-attenuating collection between Gerota’s fascia and the renal parenchyma
      • They do not usually deform the shape of the renal parenchyma, even when large
    • Subcapsular or perinephric hematoma is usually proportional to extent of injury
    • Rarely, a subcapsular hematoma may compress the kidney sufficiently to produce renal perfusion and result in hypertension –the Page kidney
  • Segmental arterial injury (infarction)
    • Wedge-shaped perfusion defect, which persists even with delayed imaging
    • Usually treated conservatively as they either resolve spontaneously or heal with small scar
  • Devascularized kidney
    • Diffuse non-perfusion of kidney
    • Most often from a clot that forms in an incompletely torn renal artery
  • Renal vein thrombosis
    • Persistent nephrogram on delayed scans
  • Active extravasation of contrast from renal artery
    • Attenuation as bright as nearby arteries

Injury

How do you recognize it

Contusion (75-80%)

Focal patchy areas of decreased enhancement

Laceration

Irregular linear hypodense parenchymal areas

Fracture

Laceration connecting two cortical surfaces

Crush injury

Multiple separated renal fragments ± perfusion

Calyceal or pelvic injury

Extraluminal contrast

Vascular pedicle injury

Wedge-shaped or diffuse non-perfusion of kidney

Subcapsular hematoma

Superficial crescentic hypodense area compressing adjacent parenchyma



Subcapsular hematoma and laceration of left kidney. This is a coronal reconstruction of a contrast-enhanced CT scan of the abdomen and pelvis. There is a subcapsular fluid collection that compresses the adjacent renal parenchyma (red arrow). In addition, there is a lucency traversing the lower pole of the kidney that represents a renal laceration.
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For this same photo without the arrows, click here


eMedicine Smith, J; Schauberger, J; Kenny, P; Cheer, A; and Lobera, A
Dahnert 5th edition