A polytraumatized patient, with blunt abdominal trauma resulting from a car accident, was brought to the emergency department, still conscious, with no signs of hypovolemic shock.
Contrast enhanced abdominal Computed Tomography (CT) revealed a liver haematoma with 4.2cm involving segments VII and VIII (Grade III according to the AAST grading system). No injuries of portal or hepatic veins were depicted. There were no signs of active extravasation of intravenous contrast or haemoperitoneum.
Liver is the most commonly injured abdominal organ in blunt trauma . Damage to the liver is the most common cause of death after abdominal injury with an overall mortality of 4.1% to 11.7% . CT is the modality of choice in assessing clinically stable patients with abdominal trauma . The CT features of blunt liver injuries are parenchymal lacerations, subcapsular and parenchymal haematomas and active haemorrhage vascular injuries . Parenchymal lacerations appear as irregular, linear or branching low-attenuation areas at contrast-enhanced CT. Lacerations that extend to the porta hepatis are commonly associated with bile duct injury and are likely to lead to the development of biloma [1,2].
Subcapsular haematoma appears as a lenticular “mass effect”-like lesion, of low-attenuation blood between the liver capsule and the enhancing liver parenchyma at contrast-enhanced CT. Subcapsular haematomas can be differentiated from free intraperitoneal blood in the perihepatic space in that the former cause indentation of the underlying liver margin, whereas the latter does not. Parenchymal haematomas are characterised by focal low-attenuation areas with irregular margins at contrast-enhanced CT [1,2].
Active haemorrhage is seen as linear high attenuation areas of extravasated contrast (85-350 HU), isodense to the enhanced vessels.
Indirect signs of liver trauma include haemoperitoneum and perihepatic clot (hyperdense clotted blood with more than 45HU).
Delayed complications include haemorrhage, abscess, pseudoaneurism and biloma .
The most widely used grading system for liver injury is the grading system established by the American Association for the Surgery of Trauma (AAST). This classification is based on the anatomic disruption of the liver, including the depth and number of lacerations and the surface area involved by subcapsular or intraparenchymal haematomas.
Grade I – laceration/subcapsular haematoma with less than 1cm deep/diameter; Grade II - laceration/subcapsular or central haematoma with 1-3cm deep/diameter; Grade III - laceration/subcapsular or central haematoma with 3-10cm deep/diameter; Grade IV - laceration/subcapsular or haematoma with more than 10cm deep/diameter; Grade V – global destruction or devascularisation; Grade VI – hepatic avulsion .
Grade I, II and III are generally treated conservatively [1,3]. The best predictor for intervention or surgery requirement is active extravasation or pseudoaneurysm . Follow-up CT is useful in monitoring conservative management and in detecting delayed hepatic complications.
In conclusion, CT can depict various patterns of liver injuries and other associated injuries that may require urgent surgical intervention in patients with blunt abdominal trauma. CT is also helpful in the follow-up of high-grade liver injuries.
Differential Diagnosis List
Focal fatty liver deposition