Liver Trauma

Etiology

A traumatic liver injury is common in both blunt and penetrating abdominal injuries. The liver’s anterior location in the abdomen, its fragile parenchyma, and the relative ease in which Gleeson’s capsule is violated makes it susceptible to injury from blunt forces. Its fixed location under the diaphragm also makes it susceptible to shear forces from deceleration injuries. The vasculature in the liver is made up of large but thin-walled vessels with high blood flow. The mechanism of injury for blunt abdominal trauma is often due to motor vehicle accidents, pedestrian accidents, and falls. Farming and industrial accidents can also lead to a number of liver injuries. In addition, the anterior location and large size relative to other abdominal organs make it prone to injury in penetrating abdominal penetrating trauma from gunshot or stab wounds. The right lobe of the liver is the most commonly injured portion in both blunt and penetrating injuries.[4]

Epidemiology

Liver injuries make up approximately 5% of all trauma admissions. The liver is the most common solid organ injured in blunt trauma, and patients with hepatic injury usually have other concomitant injuries. Mortality from hepatic trauma depends on the degree of injury. Minor liver injuries make up most hepatic trauma, with 80% to 90% being grades 1 or II. Mortality increases with the grade of injury, and grade VI liver injuries are often fatal. Liver injury is the primary cause of death in severe abdominal trauma and has a 10% to 15% mortality rate.[4]

History and Physical

Care of the patient with hepatic injury often begins in the trauma bay. First responders can give provide crucial information regarding the mechanism of injury that may help the clinician discern whether a liver injury may exist. Trauma to the anterior or lateral wall or thoracoabdominal region may raise the suspicion of a possible hepatic injury. As with all trauma patients, the evaluation must be guided with advanced trauma life support principles. The primary survey should be conducted to identify immediately life-threatening injuries. For patients with hepatic injury, the primary survey should identify the presence of hypovolemic shock from liver bleeding. Vital sign changes present in hemorrhagic shock include a narrow pulse pressure, hypotension, and tachycardia.

After the primary survey is completed, the secondary survey should be conducted by performing a head-to-toe exam that can identify any potential injuries. Patients with the liver injury can have right upper quadrant tenderness, and the presence of abdominal distention can suggest hemoperitoneum.[5][6]

Evaluation

Laboratory Evaluation

Trauma patients with the appropriate mechanism of injury that are seen in the trauma bay should receive a standard set of laboratory tests. This may include but is not limited to a comprehensive metabolic panel, complete blood count, coagulation parameters, and lactate level. In addition, liver function tests may be abnormal, although this may not be seen until several hours to days after injury.

Radiologic Evaluation

Radiologic assessment can also begin in the trauma bay with a focused assessment with sonography for trauma (FAST) exam. The FAST exam is used to identify the presence of blood in the abdominal cavity or pericardial sac. It does not identify the degree of organ injury. The FAST exam is highly operator dependent, and its sensitivity and specificity ranged from 63% to 100% and 95% to 100%. It can guide management in the trauma bay and help clinicians decide if patients with liver injuries should proceed directly to the operating room.

Patients who have responded to resuscitation and are hemodynamically stable in the trauma bay can have further imaging to help guide treatment. CT scan of the abdomen and pelvis with intravenous (IV) contrast has become almost routine in the hemodynamically stable abdominal trauma patient. It is the best modality for identifying hepatic injuries. CT allows for the identification of hepatic injury and grading of severity. It also allows the clinician to identify other abdominal injuries and quantify hemoperitoneum. Administering IV contrast with CT scan allows for identification of patients with active extravasation of blood as evidenced by a blush on the CT from the liver. This may help the clinician decide if the patient may benefit from angiographic embolization or surgical intervention. The trauma surgeon must correlate radiologic findings with a clinical presentation to guide management and take into account hemodynamic instability or peritoneal signs. 

While magnetic resonance cholangiopancreatography (MRCP) does not have a role in the acutely injured trauma patient because of its time-consuming nature, it may play a role in patients where bile duct injury or leak is suspected.[7]

Injury Grading

Radiologic findings are used to grade the degree of liver injury as defined by the American Association for the Surgery of Trauma (AAST) Hepatic Injury Scale. While a grade of liver injury does not necessarily define treatment, higher grade injuries have higher mortality and are at greater risk of failing non-operative management.[8]

Treatment / Management

Non-Operative Management

Non-operative management for blunt hepatic injury is the treatment of choice in hemodynamically stable patients as specified by the Eastern Association for the Surgery of Trauma Practice Management Guidelines. Non-operative therapy is appropriate only at a facility capable of hemodynamic monitoring, serial abdominal examinations, and an operating room that is immediately available for emergency laparotomy. Patients with blunt hepatic injury undergoing non-operative therapy must be monitored in the intensive care unit (ICU) for a period with serial hematocrits, abdominal exams, nil per os, and bed rest. How frequently and for how long this should be carried out has not been established and varies by institution. In addition, several other unanswered questions in the non-operative management of blunt hepatic trauma exist. This includes when to resume a diet, how long to wait before starting chemical deep vein thrombosis (DVT) prophylaxis, and when the patient can resume full activities.

Patients with higher injury grades are more likely to fail non-operative management, with hemodynamic instability being the leading cause of failure in 75% of patients. However, failure of non-operative therapy does not necessarily mean the patient should undergo surgery as angiographic therapy can be effective.

Non-operative therapy may play a role in very select patients with penetrating injury who are hemodynamically stable. For penetrating trauma localized to the right upper quadrant, often the result stab wounds or low-velocity gunshot wounds, with low-grade injuries may be managed non-operatively. Other abdominal injuries must be excluded in these patients. Similar to blunt hepatic injured patients, they should undergo admission to an ICU with hemodynamic monitoring, serial laboratory evaluations, and abdominal exams.[9]

Angiographic Embolization

Angiography with selective embolization is an effective treatment for patients undergoing non-operative therapy of bleeding liver injuries, especially those with blunt hepatic injuries. Success rates for angiography and embolization are as high as 83%. No clear consensus guidelines exist as to when and in which patients to perform angiography with embolization. Some trauma surgeons prefer to do angiography and embolization in any blunt hepatic injury higher than grade III. In contrast, others will only do so if there is contrast extravasation on a CT scan.[10](B2)

Operative Management

Hemodynamically unstable patients, not responsive to resuscitation, should go directly from the trauma bay to the operating room for laparotomy. In addition, patients with peritoneal signs should go to the operating room. Patients that fail non-operative therapy must undergo laparotomy. Damage control laparotomy principles should be followed in the unstable patient undergoing laparotomy. This includes first controlling hemorrhage, then controlling gastrointestinal (GI) contamination. The abdomen should be packed in all 4 quadrants, allowing for injuries to be localized and the anesthesia team to resuscitate the patient. The “lethal triad” of coagulopathy, acidosis, and hypothermia should trigger a damage control approach.

Some temporizing measures can be taken to minimize blood loss from hepatic injuries. The liver can be manually compressed together with the surgeon’s hands on each side of the fracture, allowing for the raw edges to be pushed together. Peri-hepatic packing can also be carried out by placing laparotomy pads in the space between the liver and diaphragm and around the anterior and lateral sides of the liver to reapproximate raw edges of injured parenchyma. Patients that require peri-hepatic packing have a high rate of mortality. For severe bleeding that cannot be controlled, a Pringle maneuver may be helpful. This involves placing a non-crushing vascular clamp on the porta hepatis to occlude the hepatic artery and portal vein. If this results in decreased hemorrhage, then bleeding is likely related to the hepatic inflow vessels. However, if bleeding continues despite the Pringle maneuver, then bleeding is from injury to the hepatic vein or retrohepatic inferior vena cava (IVC). The Pringle maneuver should be released every 20 to 30 minutes to allow intermittent perfusion of the hepatic maneuver. The Pringle maneuver can be combined with the finger fracture technique to control bleeding from liver lacerations.

With more destructive injuries, ligation of the feeding hepatic artery or an anatomic hepatic lobectomy may be necessary. Selective ligation of the right or left hepatic artery just beyond the bifurcation of the proper hepatic artery can be used to manage bleeding that has been localized to one of the hepatic lobes. In desperate circumstances, non-selective ligation of the common hepatic artery can be indicated. It is important to make sure that flow through the portal vein is intact prior to carrying out non-selective ligation. Given the liver’s dual blood supply, hepatic ischemia is not likely after common hepatic artery ligation. In a damage control situation, the above temporizing maneuvers may allow for rapid, temporary abdominal closure and transfer of the patient to the ICU for continued resuscitation and reversal of the “lethal trial.” Angiography with embolization can also be used as an adjunct treatment with damage control laparotomy.

In patients not undergoing damage control laparotomy, other hemostatic techniques can be used. Fractured parenchyma can be reapproximated with suture hepatorrhaphy. The hepatic wound should be explored, and any injured bile duct radicals should be identified and ligated with suture or clips. Similarly, damaged blood vessels can be identified and ligated or clipped. For grade II or III injuries, a chromic suture on a 1-0 or 2-0 blunt needle can be used to approximate the laceration. Gleeson’s capsule provides the tensile strength for the suture. For deeper lacerations, omentum can be packed into the injured parenchyma and sutured into place with simple sutures. Commercial hemostatic agents can also be placed on injured parenchyma to help maintain hemostasis. Closed suction drains can be left into place at the discretion of the surgeon to control potential bile leaks or hepatic necrosis.[11][12](B2)

Adjunct Treatments

Other therapies can be used to treat patients with traumatic liver injuries. For example, endoscopic retrograde cholangiopancreatography (ERCP) can be used to identify and treat bile duct injuries, whether done pre- or post-operatively. Stents can be placed at the time of ERCP to help treat bile duct lacerations. In addition, bile duct stents can be placed to decrease hepatic parenchymal bile leak and facilitate healing of injured bile ducts.

Interventional radiology (IR) can also be used as an adjunct for hepatic trauma. Bilomas or hepatic abscesses can develop as a result of traumatic injury or as a complication of angioembolization and hepatic necrosis. Closed suction drains can be placed by IR to drain infections or bilious fluid collections.[13]

Differential Diagnosis

• Domestic violence
• Hemorrhagic shock
• Hypovolemic shock
• Lower genitourinary trauma
• Penetrating abdominal trauma
• Pregnancy trauma
• Upper genitourinary trauma

Complications

Clinicians should be aware of several complications that can develop after liver trauma. The most common complication is bile leak and can occur in as many as 21% of patients managed operatively. Also, hepatic abscesses can develop after hepatic artery ligation or angioembolization. Hepatic necrosis occurs commonly after hepatic injury and is most likely to occur in patients undergoing angioembolization. Up to 41% of patients will have hepatic necrosis after angioembolization. These patients can present with fever and leukocytosis. Patients with mild symptoms can be treated supportively with IV fluids. At the same time, those with more serious inflammatory responses may require intervention in the form of IR placed drains or, in more serious cases, repeated operative debridement or formal hepatic resection.

Another rare complication of hepatic trauma is an arterio-biliary or porto-biliary fistula that results in hemobilia. Hemobilia can result in clot and obstruction of the biliary tree. Brisk bleeds can present similarly to classic GI bleed with the addition of jaundice and upper abdominal pain. Hemobilia can be treated with selective angioembolization. More severe cases may necessitate operative intervention with ligation of the feeding vessel or anatomic liver resection.[13]