Hepatic and Biliary Trauma

1

How often is the liver injured in trauma?

The liver is both large and central, so it is vulnerable to blunt trauma and an easy target for penetrating wounds. It is the most frequently injured intraabdominal organ in trauma.

2

What are the determinants of mortality after acute liver injury?

The mechanism of injury, grade of injury, and the associated abdominal organs injured determine mortality. The mortality for stab wounds to the liver is 2%; for gunshot wounds, 8%; and for blunt injuries, 15%. The mortality rate for isolated grade III hepatic injuries is 2%; for grade IV, 20%; and for grade V, 65%. Retrohepatic vena cava injuries carry mortality rates of 80% for penetrating trauma and 95% for blunt trauma.

3

What history and physical signs suggest acute liver injury?

Any patient sustaining blunt abdominal trauma (BAT) with hypotension must be assumed to have a liver injury until proven otherwise. Specific signs that increase the likelihood of hepatic injury are contusion over the right lower chest, fracture of the right lower ribs (especially posterior fractures of ribs 9–12), and penetrating injuries to the right lower chest (below the fourth intercostal space, flank, and upper abdomen). Physical signs of hemoperitoneum may be absent in as many as one-third of patients with significant hepatic injury.

4

What diagnostic tests are helpful in confirming acute liver injury?

Diagnostic peritoneal lavage is sensitive for hemoperitoneum (99%), but not specific for liver injury. Ultrasound (US) is highly sensitive in identifying >200 mL of intraperitoneal fluid. It is noninvasive and may be repeated at frequent intervals, but it is relatively poor for staging liver injuries. Contrast-enhanced US is in development at the moment. Abdominal computed tomography (CT) scan is used in patients who are hemodynamically stable who are candidates for nonoperative management. Grading of liver injuries by CT scan is useful in determining the success rate of nonoperative management because higher-grade injuries are more likely to require intervention.

5

What is the role of hepatic angiography?

Selective hepatic artery embolization is effective therapy for hepatic arterial bleeding, both for avoidance of surgery and for recurrent postoperative bleeding. Embolization should be considered for patients with active contrast extravasation into the peritoneum seen on CT scan because they are less likely to tamponade.

6

How many anatomic lobes are present in the liver? What is their topographic boundary?

The Brisbane nomenclature has been developed to standardize the way liver anatomy is defined, based on three orders of divisions. The first order of division is the right and left hemiliver. The boundary between the hemilivers lies in an oblique plane extending from the gallbladder fossa anteriorly to the inferior vena cava (IVC) posteriorly. The next order of division is based on the watershed areas between the hepatic artery and bile duct branches. While there are no visible landmarks to identify the right segments of the liver, the left hemiliver is divided into two segments via the umbilical fissure. These sections are further divided into segments that have no distinct topical anatomic markers aside from segment one (caudate segment), which is wrapped around the vena cava. These segments are numbered I–VIII, based on the portal vein.

7

What is the blood supply to the liver and the relative contribution of each structure to hepatic oxygenation?

The hepatic artery supplies approximately 30% of the blood flow to the liver and 50% of its oxygen supply. The portal vein provides 70% of the liver’s blood flow and 50% of its oxygen. The relative significance of arterial flow in cirrhotic patients is greater; therefore, hepatic artery ligation is not recommended in patients with cirrhosis.

8

What are the most common variations in hepatic arterial supply to the right and left lobes of the liver?

In most people, the common hepatic artery originates from the celiac axis and divides into right and left hepatic arterial branches within the porta hepatis. Approximately 15% of people have a replaced right hepatic artery (sole arterial supply to the right lobe) that originates from the superior mesenteric artery (SMA). A replaced right hepatic artery always supplies a cystic artery; thus, ligation should be followed by cholecystectomy. A replaced left hepatic artery (approximately 15% of people) arises from the left gastric artery; it may be the sole blood supply to the left lobe or may contribute to blood supply in conjunction with a normal left hepatic artery. In 5% of people, the hepatic arterial supply does not arise from the celiac axis. In these people, either the right and left hepatic arteries are replaced or a single main hepatic trunk derives from the SMA.

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