Based on the mechanism of injury, liver trauma is classified as penetrating or blunt. Penetrating wounds, constituting more than half of cases, are typically due to projectiles (such as bullets or shrapnel) or knives. In civilian practice, most of these tend to be clean wounds that are dangerous because of intra-abdominal bleeding but do not result in much devitalization of liver tissue. In contrast, high-velocity projectiles are associated with greater energy that is transferred to the abdominal viscera and can shatter the parenchyma, even if the projectile does not enter the liver directly.
Blunt trauma can be inflicted by a direct blow to the upper abdomen or lower right rib cage or can follow sudden deceleration, as occurs with a fall from a great height. Most often a consequence of automobile accidents, direct blunt trauma tends to produce explosive bursting wounds or linear lacerations of the hepatic surface, often with considerable parenchymal destruction. The stellate, bursting type of injury tends to affect the posterior and superior aspect of the right liver (segments VI, VII, and VIII) because of its relatively vulnerable location, convex surface, fixed position, and concentration of hepatic mass. Damage to the left lobe is much less common than damage to the right. Injuries that involve shearing forces can tear the hepatic veins where they enter the liver substance, producing an exsanguinating retrohepatic injury in an area difficult to surgically expose and repair. The staging system used to categorize liver injuries and provide a common language in order to allow comparisons of results of treatment between institutions.
Increase by one grade when there are two or more injuries to the liver. Grading applied based on best available evidence, whether from x-rays, operative findings, or autopsy findings.
The principal surgical goals are to stop bleeding and debride devitalized liver. Because some degree of liver failure is common postoperatively, efforts should be made during each step to maintain adequate oxygenation and perfusion of the liver. Also, when one is debriding liver tissue, care should be taken to avoid injury to the vascular supply of adjacent viable parenchyma.
Symptoms and Signs of liver trauma
The clinical manifestations of liver injury are those of hypovolemic shock, ie, hypotension, decreased urinary output, low central venous pressure, and, in some cases, abdominal distention.
With major injuries, particularly those associated with disruption of hepatic veins, the rate of blood loss is usually so rapid that anemia does not develop. Leukocytosis greater than 15,000/L is common following rupture of the liver from blunt trauma.
CT scans should be obtained in most stable patients suspected of having a hepatic injury. The scans demonstrate the extent of the injury and provide a rough estimate of the amount of blood loss. The findings are useful for triaging, since minor injuries rarely require surgical treatment whereas extensive ones usually do. One must exercise caution, however, in using CT estimates of injury grade, since they correlate poorly (they both understage and overstage) with what is found at surgery.
Sonography has not been helpful other than as the rapid abdominal abdominal sonogram to identify fluid in the abdomen. It does not help to define the injury. Angiography is generally not helpful in the acute setting but may be used to diagnose and treat specific postinjury problems, such as hemobilia.
Treatment of liver trauma
Patients with stable minor liver injuries (and no associated injuries requiring exploration) may be managed expectantly unless symptoms or signs of bleeding appear. The CT findings in patients who may be considered for nonoperative management include contained subcapsular, intrahepatic hematoma, unilobar fracture, absence of devitalized liver, minimal intraperitoneal blood, absence of injuries to other intra-abdominal organs. Serial CT scans should be obtained to verify that the lesion is stable rather than expanding.
Most patients have CT or clinical evidence of active bleeding or a major injury, however, and require prompt exploration.
Most lacerations have stopped bleeding by the time operation is performed. In the absence of active hemorrhage, these wounds need not be sutured. Active bleeding should be managed by clipping or direct suture of identifiable vessels, if possible, rather than by mass ligatures. Subcapsular hematomas often overlie an active bleeding site or parenchyma in need of debridement and should be explored even though the injury appears to be tamponaded and of limited severity. Blunt liver trauma associated with amounts of parenchymal destruction may be particularly difficult to manage. Rarely, a very severe pulverizing injury requires formal lobectomy.
Temporary occlusion of the hepatic artery, portal vein can be done quickly by placing a vascular clamp around the entire hepato-duodenal ligament (Pringle’s maneuver). This can be done for periods of 15–20 minutes and reduce the hemorrhage sufficiently to permit more accurate ligation of bleeding vessels. With major hepatic venous injuries, however, a Pringle maneuver has little effect, and precise repair of the injury may not be possible. Absorbable gauze mesh (eg, polyglycolic acid) can sometimes be wrapped around an injured lobe, sutured in a way that maintains pressure and tamponades the bleeding; this is difficult to accomplish without rendering the involved liver ischemic, however, and such an approach is rarely applicable. In some cases, control of arterial hemorrhage requires ligation of the hepatic artery or one of the accessible lobar branches in the hilum.
The most difficult problems involve lacerations of the major hepatic veins behind the liver. With such injuries, temporary clamping of the inflow vessels will not slow the bleeding to allow inspection and repair of the injured vessels. For persistent bleeding, the abdominal incision can be extended into a median sternotomy to improve exposure. An ancillary technique, which is used only rarely, is to place a tube through the atrial appendage into the inferior vena cava past the origin of the hepatic veins. Appropriately placed ligatures around the vena cava permit total isolation of the liver circulation without interrupting venous return from the lower extremities to the heart. Resection of the right liver improves exposure of the retrohepatic vena cava but is a difficult to perform in the face of overwhelming hemorrhage.
In many cases, when bleeding is difficult to control and especially when other injuries must be addressed, the best strategy is to pack the liver to achieve hemostasis. The packs are generally left in place for 48–72 hours, during which time the patient remains sedated and intubated in the intensive care unit where adequate resuscitative measures are undertaken. The packs are removed in the operating room; if persistent bleeding is noted, definitive repair of the injury can then be performed.
The majority of patients who come to operation require little in the way of surgical intervention to control bleeding; drainage of substantial liver lacerations and other injuries is reasonable since bile leakage can occur. Suture ligation of bleeding hepatic vessels and debridement of devitalized tissue are indicated in about 30% and 10% of cases, respectively. More extensive procedures are indicated even less often.
Penetrating injuries that also involve the small bowel or colon may result in contamination of perihepatic fluid or devitalized liver tissue, leading to a subhepatic abscess. Placement of drains may help prevent this problem, but a high index of suspicion should be maintained.
Postoperative Complications of liver trauma
With present techniques, hemorrhage at laparotomy is rarely uncontrollable except with retrohepatic venous injuries. Patients who rebleed from the liver wound after initial suture ligation should be treated by reexploration or packing; rarely is a major resection required. Angiography and CT scanning may provide useful diagnostic information preoperatively in such patients. Subhepatic sepsis develops in about 20% of cases; it is more frequent if lobectomy has been done.
Hemobilia may be responsible for gastrointestinal bleeding in the postoperative period and can be diagnosed by selective angiography. Treatment consists of embolization through the arteriography catheter.