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Imaging and trauma

Created: 24/9/2005


Imaging and renal trauma


  • Urinary tract involved in 10-20% of major trauma from blunt or penetrating injuries
  • Kidney most commonly injured organ if the urinary tract – 8-10% of abdominal injuries
  • 90% renal injuries from blunt trauma, 10% from penetrating injuries

American Association of Surgery (AAST) renal injury scale

Important in predicting need for surgery to remove or repair kidney

Depends on

  • Depth of injury
  • Vessel involvement
  • Collecting system involvement

1 Contusions, non-expanding subcapsular haematoma

2 Non-expanding perinephric haematoma, cortical laceration <1cm depth without collecting system involvement

3 Cortical laceration >1cm depth without collecting system involvement

4 Laceration through cortico-medullary junction into collecting system, segmental renal artery or vein injury with contained haematoma

5 Shattered or devascularised kidney, PUJ avulsions, complete laceration or thrombus of renal artery or vein

NB. Primary conservative management is associated with lower nephrectomy rate and preservation of renal function without an increase in immediate or long-term morbidity

Studies exist which show in the absence of haemodynamic instability, large devitalised segments, large lacerations to collecting system or ureteric disruption, or other grade 5 injuries, patients can be managed conservatively with close observation

Types of imaging


  • Contrast-enhanced CT is imaging modality of choice in evaluation of renal injuries
  • Most comprehensive study-accuracy in diagnosis of blunt trauma as high as 97.6% [1]
  • More sensitive than IVU, USS or angiography [2]
  • Can identify:
    • Parenchymal lacerations
    • Urinary extravasation
    • Size and extent of surrounding haematoma
    • Depth and site of renal lacerations
    • Associated intra-abdominal injuries
    • Status of contralateral kidney
    • Sites of active arterial bleeding (IV contrast extravasation)
  • NB. Delayed films should be performed to identify urinary extravasation and reduce the chance of missing a PUJ disruption in cases where there is significant perinephric fluid or deep lacerations


  • Less sensitive than CT in identifying parenchymal injuries and urinary extravasation
  • Unable to detect injuries outside the renal tract
  • Most significant findings are non-function and extravasation
  • Can be used intra-operatively (one-shot) in unstable patients who require surgery and are not suitable for pre-op CT, to provide information on injured kidney and function of contralateral side [3]


  • Usually not practical in acute setting
  • Can be useful if CT in contra-indicated eg. Iodine anaphylaxis/allergy


  • Low sensitivity for detecting renal injury (as low as 22% in some studies [4]), retroperitoneal blood and hollow organ injury
  • Can detect free fluid, but cannot distinguish between urine and blood or determine source of bleeding [5]

Indications for Imaging

Penetrating Trauma:

  • Clinical suspicion of renal trauma regardless of haematuria
  • NB 1/3 of patients with penetrating trauma who are haemodynamically stable without haematuria have significant renal injury [6]

Blunt trauma:

  • Macroscopic haematuria
  • Haemodynamically unstable with microscopic haematuria [7]
  • Associated injuries suggestive of renal trauma eg. lower rib fractures [6]
  • NB. 0.1% of patients with blunt trauma, microscopic haematuria and normal cardiovascular parameters have significant renal trauma

Imaging for trauma the remainder of the urinary tract


  • <1% of all trauma to urinary tract
  • Penetrating injuries more common than blunt
  • Should be suspected in all cases of penetrating trauma especially gunshot wounds and deceleration injuries
  • Contrast-enhanced delayed CT modality of choice for initial assessment of ureteric injury in patients with major injuries


  • Indicators of bladder injury include:
    • Blood at urethral meatus
    • Macroscopic haematuria
    • Abdo-suprapubic tenderness and distension
    • Inability to void
    • Suprapubic bruising
    • Perineal swelling/haeamatoma
    • Free fluid on CT/USS
  • Pelvic fracture and macroscopic haematuria requires immediate cystography in blunt trauma patients
  • NB. 90% of extraperitoneal- and 10% of intraperitoneal bladder ruptures are associated with pelvic fractures
  • Retrograde cystography is traditional diagnostic procedure; however CT cystography is reported to be 95% sensitive and 100% specific [8] and is therefore the modality of choice for bladder injuries in trauma patients undergoing CT for associated injuries
  • NB. IVU is inadequate with high false negative rate


  • Retrograde urethrography modality of choice for anterior and posterior injuries

External genitalia

  • Mechanism of trauma and examination important
  • Macro- or microscopic haematuria associated with genital trauma requires retrograde urethrography in males and cystoscopy in females to exclude urethral/bladder injury
  • Penetrating trauma usually requires exploration
  • MRI is useful for identifying lacerations to the tunica albuginea and subsequent need for surgery in blunt penile trauma. Can also identify associated injuries to the spongiosum and urethra
  • For scrotal injuries it is important to distinguish between testicular rupture, haematocele, and haematoma in the tunica vaginalis
  • Ruptured testes can be salvaged in 90% of patients if repaired within 72hrs, compared to 55% after this [9]
  • USS is modality of choice for scrotal injuries
  • NB. Despite sensitivity of USS, if clinical suspicion of significant testicular injury exists surgical exploration should be performed

Paediatric trauma

  • Children more prone to urinary trauma due to
    • Larger kidneys relative to abdominal size
    • Less perirenal fat
    • Persisitance of foetal lobulation allowing for easier separation of renal units
  • Threshold for imaging in children should be low
  • CT is appropriate in
    • Blunt trauma with any degree of haematuria
    • Patients with abdominal injuries regardless of urinalysis
    • Patients in whom there is a high index of suspicion of renal trauma in light of the mechanism of injury


1. Novelline, R., J. Rhea, and T. Bell, Helical CT of abdominal trauma. Radiol Clin North Am, 1999. 37(3): p. 591-612.

2. Bretan, P., et al., CT staging of renal trauma: 85 consecutive cases. Journal of Urology, 1986. 136(6): p. 561-565.

3. Morey, A., et al., Single shot intraoperative excretion urography for the immediate evaluation of renal trauma. Journal of Urology, 1999. 161: p. 1088-1092.

4. McGahan, J., et al., The use of ultrasonography in the patient with acute renal trauma. J Ultrasound Med, 1999. 18: p. 207-213.

5. Smith, J. and P. Kenney, Imaging of renal trauma. Radiol Clin North Am, 2003. 41: p. 1019-1035.

6. McAndrew, J. and J. Corriere, Radiographiv evaluation of renal trauma: evaluation of 1103 consecutive patients. Br J Urol, 1999. 73: p. 352-354.

7. Mee, S. and J. McAninch, Indication for radiographic assessment in suspected renal trauma. Urol Clin North Am, 1989. 16: p. 187.

8. Deck, A., et al., CT cystography for the diagnosis of traumatic bladder rupture. Journal of Urology, 2000. 164(1): p. 43-46.

9. Krone, K. and B. Carroll, Scrotal ultrasound. Radiol Clin North Am, 1985. 23: p. 121-139.

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