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Renal trauma

    • Kidney is the most injured urological organ in trauma
    • 1 – 5 % of all trauma patients have renal injury
    • 24 % of all solid organ injury is renal
    • 50 % of renal injured patients will have concomitant injuries
    • Renal trauma (and all trauma) is more common in young men
    • > 90 % of renal trauma in Australia is blunt trauma
    • Vast majority of renal injuries can be managed conservatively – only 5 % need surgical intervention

    Assessment of renal trauma

    As per standard trauma assessment with particular attention to:

    • Haemodynamic stability and Hb
    • Presence of contra-lateral kidney on imaging
    • History of renal disease or abnormal renal function
    • Anticoagulation
    • Other injuries and overall status

    Imaging in renal trauma

    “Traditional” indications for imaging in renal trauma:

    • Visible haematuria
    • Non visible haematuria with an episode of hypotension
    • Significant mechanism – rapid deceleration injury
    • Penetrating trauma
    • Clinical suggestion of renal injury – flank bruising, rib injury, abdominal distension, palpable mass etc

    In reality, almost all trauma patients will have had a trauma protocol CT prior to urological involvement, consisting often of an arterial and portal venous phase, but usually no delayed phase.

    The goals of imaging in renal trauma are:

    • Identify and grade the injury
    • Document any pre-existing renal pathology
    • Demonstrate a contra-lateral kidney
    • Identify other injuries

    The best imaging is multi-phase CT with arterial phase (for vascular injury or arterial extravasation), venous/nephrogenic phase (for parenchymal lacerations) and a delayed phase (for collecting system injury).

    AAST grading for renal trauma

    If multiple injuries present – use highest grade.

    If bilateral injuries, advance grade one grade, up to grade 3.

    Management – non operative

    Non operative management is the standard of care for grade 1 – 3 injuries, and probably most grade 4 injuries.

    Comprises:

    • A period of bed rest (until urine macroscopically clear)
    • Mechanical DVT prophylaxis
    • Serial repeat examinations
    • Serial bloods monitoring Hb
    • Repeat imaging
      • Can be safely omitted for grade 1 – 3 injuries if no change in clinical status
      • Probably should be done for higher grade injuries and penetrating injuries after 3 – 5 days, and definitely for any change in clinical symptoms, dropping Hb, fever or abdominal distension.

    Collecting system injury

    Relatively small urine leaks may be managed conservatively as above.

    If there is a large volume leak, persistent leak on repeat imaging, or complications such as enlarging collection, fever, increasing pain, infection or other concerns, drainage should be achieved.

    • Ureteric stent
    • Nephrostomy
    • Percutaneous urinoma drain

    NB if placing ureteric stent, probably need to leave urethral catheter for a period also to prevent reflux of urine.

    Penetrating trauma

    Less likely to be successfully managed non operatively – 50 % of penetrating injuries can be managed conservatively, and only 40 % of gunshots.

    Majority of low grade stab wounds posterior to the anterior axillary line can be safely managed conservatively if the patient is stable.

    Grade 3 or higher injuries should be watched closely – these have a higher chance of failing conservative management.

    Angioembolisation

    Significant increase in use of interventional radiology techniques.

    No clear data driven consensus on its indications and current use is heterogenous.

    Its most useful role seems to be in high grade renal trauma to prevent nephrectomy but still control bleeding.

    Definite or accepted indications for use include:

    • Contrast extravasation or blush signifying active bleeding, in an otherwise stable patient
    • Arterio-venous fistula or pseudoaneurysm

    Indications for surgical exploration

    • Grade 5 injury (shattered kidney) or vascular injury
    • Persistent haemodynamic instability (poor response to fluid resuscitation)
    • Expanding or pulsatile retroperitoneal haematoma at laparotomy
    • PUJ avulsion

    Relative indications:

    • Persistent bleeding following embolisation
    • Devitalised parenchyma on follow up imaging with persistent urine leak

    Complications following renal trauma

    Follow up after renal trauma

    Lifelong blood pressure surveillance.

    Initially 6 weekly ultrasounds to check structural integrity.

    Can probably return to sport at 3 months if kidney is structurally sound (expert opinion).

    One shot IVP

    Done to confirm the presence of a functioning contra-lateral kidney prior to exploration of nephrectomy in trauma (if no CT pre-op) – 2 mg / kg IV contrast, then x-ray 10 minutes later.

    Post renal trauma hypertension

    Renal trauma related hypertension (persisting 30 days after injury) may occur in 5 – 15 % of grade 3+ injuries (rarely seen in grade 1-2).

    Mechanisms of post trauma hypertension:

    • Compression of renal parenchyma leading to increased renin release (Page type kidney)
    • Parenchymal ischaemia leading to renin release
    • Trauma induced vascular anomalies – i.e., AV fistula or pseudoaneurysm
    • Significant renal scarring

    Renin mediated hypertension generally treated with ACE-I or ARBs.

    Page type kidney may refer to a subcapsular fluid collection (haematoma/urinoma) compressing renal parenchyma leading to renin mediated hypertension.

    • This can be acute or chronic.