Traumatic renal injury is a relatively uncommon occurrence, which is found in 1-5% of all traumas¹. They are typically caused by blunt injury mechanisms, in particular, motor vehicle accidents and falls from height.

Traumatic renal injury can be graded from 1 though to 5. The grading system is defined as follows²:

• Grade I - Contusion or non-expanding subcapsular hematoma; No laceration
• Grade 2 - Non-expanding perirenal hematoma; Cortical laceration <1cm deep without extravasation
• Grade 3 - Cortical laceration > 1 cm without urinary extravasation
• Grade 4 - Laceration through corticomedullary junction into collecting system OR Vascular segmental renal artery or vein injury with contained hematoma
• Grade 5 - Shattered kidney OR renal pedicle injury or avulsion

Stable patients with grade 1 to 4 lacerations tend to be managed conservatively. Grade 5 injuries, or unstable patients with lesser grade injuries require intervention. Unstable patients may have life-threatening hemorrhage, renal pedicle avulsion or expanding retroperitoneal hematomas.

Management options are either with open surgical exploration or interventional angioembolisation. Typically, nephrectomy is preferred over repair, unless there is a contra-indicating factor such as a solitary kidney or bilateral kidney injury.

In this particular case, note the hypoattenuating blood which lies dependently in Gerota's fascia. There is no active extravasation of contrast, which suggests that this is old blood lying within the fascia.

Liver injury is a common finding in many types of trauma³. This is because of its anterior abdominal location, as well as fragile parenchyma.

Investigations into traumatic liver injury involves focused assessment for trauma using ultrasound (FAST scans), CT or with diagnostic peritoneal lavage. Imaging such as radiography may reveal chest fractures or splenic lacerations, both of which are commonly associated injuries.

Traumatic liver injury can be divided into six categories according to the American Association for the Surgery of Trauma⁴. This particular patient had a grade III hepatic laceration.

• Grade I – Hematoma: subcapsular <10 percent surface area. Laceration: capsular tear <1 cm parenchymal depth
• Grade II – Hematoma: subcapsular 10 to 50 percent surface areaintraparenchymal <10 cm in diameter. Laceration: capsular tear 1 to 3 cm parenchymal depth, <10 cm in length.
• Grade III – Hematoma: subcapsular >50 percent of surface area or ruptured subcapsular or parenchymal hematoma; intraparenchymal hematoma >10 cm or expanding. Laceration >3 cm in depth.
• Grade IV – Laceration: parenchymal disruption involving 25 to 75 percent of a hepatic lobe, or 1 to 3 Couinaud segments.
• Grade V – Laceration: parenchymal disruption of >75 percent of a hepatic lobe, >3 Couinaud segments within a single lobe. Vascular: juxtahepatic venous injuries (retrohepatic vena cava, central major hepatic veins).
• Grade VI – Hepatic avulsion.

Patients are managed based on their degree of hemodynamic stability. This is regardless of the grading of the injury. Stable patients are usually managed conservatively with supportive care. If there is extravasation of IV contrast, these lesions are usually embolized via interventional hepatic embolization.

An haemodynamically compromised patient with a liver laceration is an indication for operative management. This can involve both damage control surgery or liver resection in the severely compromised patient.

In this case, note the homogeneous hypodense fluid lying anterior to the liver. This potential space is usually the first area where hepatic fluid will build up. Inferiorly, note that the fluid becomes hyperdense and heterogeneous adjacent to the left 10th and fractured 11th rib. This represents active extravasation of intravenous contrast, further supporting the aformentioned liver injury.

Case contributed by A/Prof. Pramit Phal.