Liver trauma

General

Liver injuries are fortunately uncommon because of the liver’s position under the diaphragm protected by the chest wall. However, when they do occur they are serious injuries associated with a significant morbidity and mortality, even with prompt and appropriate management. Liver trauma can be divided into blunt traumatic injuries which produce contusions, lacerations and avulsion injuries to the liver, and penetrating injuries, such as stab and gunshot wounds. The liver is typically one of many organs to be damaged, the chest or pericardium often being involved with penetrating injuries and the spleen or kidney with blunt trauma.

Diagnosis of liver injury

The liver is an extremely well-vascularised organ and blood loss is therefore the major early complication of liver injuries. Clinical suspicion of a possible liver injury is essential as a laparotomy by an inexperienced surgeon with inadequate preparation preoperatively is doomed to failure. All lower chest and upper abdominal stab wounds should be suspect, especially if considerable blood volume replacement has been required. Similarly, severe crushing injuries to the lower chest or upper abdomen often combine rib fractures, haemothorax and damage to the spleen and/or liver. Patients with a pene­trating wound will require a laparotomy and/or thoracotomy once active resuscitation is underway. Owing to the oppor­tunity for massive ongoing blood loss and the rapid devel­opment of a coagulopathy, the patient should be directly transferred to the operating suite whilst blood products are obtained and volume replacement is ongoing. Patients with blunt trauma who are haemodynamically stable but have objective clinical signs, such as upper abdominal tenderness and guarding, should have an oral and intravenous contrast enhanced CT scan of the chest and abdomen. This will demonstrate evidence of parenchymal damage to the liver or spleen as well as associated traumatic injuries to their feeding vessels. Free fluid can also be clearly established and a diagnostic aspirate performed. The chest scan will help to exclude injuries to the great vessels and demonstrate damage to the lung parenchyma. Additional investigations which may be of value include peritoneal lavage, which can confirm the presence of haemoperitoneum, and laparoscopy, which can demonstrate an associated diaphragmatic rupture.

Initial management of liver injuries

Penetrating

The initial management of a patient with an upper abdominal penetrating injury is the basis of resuscitation. The initial survey assesses the patients airway patency, breathing pattern and circulation. Peripheral venous access is gained with two large-bore cannulae and blood sent for cross match of 10 units of blood, full blood count, urea and electrolytes, liver function tests, clotting screen, glucose and amylase. Initial volume replacement should be with colloid or 0-negative blood if necessary. Arterial blood gases should be obtained and the patient intubated and ventilated if the gas exchange is inadequate. Intercostal chest drains should be inserted if associated pneumothorax or haemothorax is suspected. Once initial resuscitation has been commenced the patient should be transferred to the operating theatre with further resuscitation being performed on the operating table. The necessity for fresh frozen plasma and cryoprecipitate should be discussed with the blood transfusion service immediately the patient arrives, as these patients rapidly develop irreversible coagulopathies due to a lack of fibrinogen and clotting factors. Standard coagulation profiles are inadequate to evaluate this acute loss of clotting factors, and factors should be given empirically, aided by the results of thromboelastography (TEG), if available (Fig. 52.9).

Blunt trauma

With severe blunt injuries the plan for resuscitation and management is as outlined above for penetrating injuries. For the patient whose vital signs are normal, imaging may be performed to evaluate further the nature of the injury. The basic surgical management differs between penetrating and blunt injuries thought to involve the liver. Penetrating injuries should be explored, whereas blunt injuries can be treated conservatively. The indication for discontinuing conservative treatment for blunt trauma would be evidence of ongoing blood loss despite correction of any underlying coagulopathy and the development of signs of generalised peritonitis.

The surgical approach to liver trauma

The surgical approach is partly dictated by the nature of the suspected injury. Good access is vital. A rooftop incision gives excellent visualisation of the liver and spleen and, if necessary, can be extended upwards for a median sternotomy. A stab incision in the liver can be sutured with a fine absorbable monofilament suture. If necessary, this may be facilitated by producing vascular inflow occlusion by placing an atraumatic clamp across the foramen of Winslow (the Pringle manoeuvre). Lacerations to the hepatic artery should be identified by placing an atraumatic bulldog clamp on the proximal vessel prior to repair with 5/0 or 6/0 Prolene suture. If unavoidable the hepatic artery may be ligated, although parenchymal necrosis and abscess formation will result in some individuals. Portal vein injuries should be repaired with 5/0 Prolene, again with exposure of the vessel being facilitated by the placement of an atraumatic vascular clamp. The blunt trauma of deceleration injuries often produces lacerations of the liver parenchyma adjacent to the anchoring ligaments of the liver. These may be amenable to suture with an absorbable monofilament suture. -Again, inflow occlusion may facilitate this suturing and, if necessary, the sutures can be buttressed to prevent them cutting through the liver parenchyma. With more severe deceleration injuries a portion of the liver may be avulsed from anterior to posterior. These injuries are more complex as they are associated with a devitalised portion of the liver and often major injuries to the hepatic veins and IVC. The initial management of liver injuries is to pack the liver to produce haemostasis. This is effective for the majority of liver injuries if the liver is packed against the natural contour of the diaphragm by packing from below Large abdominal packs should be used to ease their removal, and the abdomen closed to facilitate compression of the parenchyma. Care should be taken to avoid over-zealous packing as this may produce pressure necrosis on the liver parenchyma. Crush injuries to the liver often result in large parenchymal haematomas and diffuse capsular lacerations. Suturing is usually ineffective, and packing is the most useful method of providing haemostasis. Necrotic tissue should be removed, but poorly perfused but viable liver left in situ. If packing is necessary the patient should have the packs removed after 48 hours, and commonly no further surgical intervention is required. Antibiotic cover is advisable and full reversal of any coagulopathy is essential. If a major liver vascular injury was suspected at the time of the initial laparotomy then referral to a specialist centre should be considered. A common surgical approach under these circumstances would be to place the patient on veno-venous bypass using cannulae in the femoral vein via a long saphenous cutdown and being returned, via a roller pump, to the superior vena cava (SVC) via an internal jugular line. Veno­venous bypass allows the IVC to be safely clamped to facilitate caval or hepatic vein repair. A rapid-infuser blood transfusion machine facilitates the delivery of a large volume of blood instantaneously. Once prepared, the patient is re laparotomised via the rooftop incision with a midline extension to the xiphisternum. The liver is mobilised by division of the supporting ligaments, and complete vascular isolation of the liver achieved by occluding the hilar inflow and the IVC above the renal veins and at the level of the diaphragm with atraumatic vascular clamps. Venous return is provided by the veno-venous bypass. Warm ischaemia of the liver is tolerated for up to 45 minutes, allowing sufficient time in a blood-free field for repair of injuries to the IVC or hepatic veins.

Other complications of liver trauma

By far the most important complication of blunt or penetrating trauma to the liver is sudden massive blood loss. There are, however, other presentations and complications which require specific investigation and treatment. A subcapsular or intrahepatic haematoma requires no specific intervention and should be allowed to resolve spontaneously. Attempts to aspirate these lesions may result in the development of a liver abscess due to contamination. Abscesses may also form as a result of secondary infection of an area of extensive parenchymal ischaemia, especially after penetrating trauma. Treatment under these circumstances is with appropriate systemic antibiotics and aspiration under ultrasound guidance once the necrotic tissue has liquefied. Biliary fistulae are a rare but important complication of liver trauma and may be difficult to control. The main aspects to management are to drain any intraperitoneal bile collections externally by percutaneous drainage under ultrasound guidance. This is followed by endoscopic or percutaneous cholangiography to determine the site of the biliary fistula and decompress the biliary tree by nasobiliary drainage or endoprosthesis insertion. If this fails to control the fistula the affected portion of the liver may require to be resected. Late vascular complications include hepatic artery aneurysms and arteriovenous and arteriobiliary fistulae (Figure 52.10). These are best treated nonsurgically by a specialist hepatobiliary interventional radiologist. The feeding vessel can be embolised transarterialy. Evidence of liver failure may be seen with extensive liver trauma. If the blood supply and biliary drainage of the liver are intact this will usually reverse with conservative supportive treatment.

Long-term outcome of liver trauma

The capacity of the liver to recover from extensive trauma is remarkable, and parenchymal regeneration occurs rapidly. Late complications are rare but the development of biliary tract strictures many years after recovery from liver trauma has been reported. The treatment depends on the mode of presentation and the extent and site of stricturing. A segmen­tal or lobar stricture associated with atrophy of the corresponding area of liver parenchyma and compensatory hypertrophy of the other liver lobe may be treated expectantly. A dominant extra hepatic bile duct stricture associated with obstructive jaundice may be treated initially with endo­biliary balloon dilatation or stenting but will usually require surgical correction using a Roux-en-Y hepatodocho­jejunostomy.