You are in: eMedicine Specialties > Radiology > GASTROINTESTINAL Liver, TraumaArticle Last Updated: Mar 19, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR, LRCP, Chairman of Medical Imaging, Professor of Radiology, NGHA, King Fahad National Guard Hospital, King Abdulaziz Medical City, Riyadh, Saudi Arabia Ali Nawaz Khan is a member of the following medical societies: American Institute of Ultrasound in Medicine, Radiological Society of North America, Royal College of Physicians, Royal College of Physicians and Surgeons of the United States, Royal College of Radiologists, and Royal College of Surgeons of England Coauthor(s): Hemant Vadeyar, MBBS, Consulting Hepatobiliary and Pancreatic Surgeon, North Manchester General Hospital; Sumaira MacDonald, MBChB, PhD, MRCP, FRCR, Lecturer, Sheffield University Medical School; Endovascular Fellow, Sheffield Vascular Institute; Muthusamy Chandramohan, MBBS, DMRD, FRCR, Consultant Radiologist, Bradford Teaching Hospitals, UK Editors: Neela Lamki, MD, Professor, Department of Radiology, Sultan Qaboos University, Oman; Adjunct Professor, Department of Radiology, Baylor College of Medicine; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Spencer B Gay, MD, Professor of Radiology, Director of Body Computed Tomography, Department of Radiology, University of Virginia Health Sciences Center; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; John Karani, MBBS, FRCR, Consulting Staff, Department of Radiology, King's College Hospital, London Author and Editor Disclosure Synonyms and related keywords: liver trauma, liver injury, abdominal injury, abdominal trauma, blunt abdominal trauma, blunt abdominal injury, hepatic injury, blunt hepatic injury, hepatic trauma, central liver hematoma, subcapsular hematoma, intrahepatic hematoma, hepatic laceration, hepatic contusion, hepatic vascular disruption, bile duct injury, penetrating abdominal trauma, biliary disruption INTRODUCTIONSection 2 of 12
  BackgroundThe liver is the largest solid abdominal organ with a relatively fixed position, which makes it prone to injury. The liver is the second most commonly injured organ in abdominal trauma, but damage to the liver is the most common cause of death after abdominal injury. The most common cause of liver injury is blunt abdominal trauma, which is secondary to motor vehicle accidents in most instances. In the past, most of these injuries were treated surgically. However, surgical literature confirms that as many as 86% of liver injuries have stopped bleeding by the time surgical exploration is performed, and 67% of operations performed for blunt abdominal trauma are nontherapeutic. Imaging techniques, particularly computed tomography (CT) scanning, have made a great impact on the treatment of patients with liver trauma, and use of these techniques has resulted in marked reduction in the number of patients requiring surgery and undergoing nontherapeutic operations. Almost 80% of adults and 97% of children are treated conservatively by using careful follow-up imaging studies.1, 2 For excellent patient education resources, visit eMedicine's Liver, Gallbladder, and Pancreas Center and Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education article Abdominal Pain in Adults. PathophysiologyThe liver is the largest intra-abdominal solid organ and is enclosed anteriorly and laterally by the rib cage. The large size of the liver, its friable parenchyma, its thin capsule, and its relatively fixed position in relation to the spine make the liver particularly prone to blunt injury. As a result of its larger size and proximity to the ribs, the right lobe is injured more commonly than the left. Various biomechanical mechanisms have been proposed in the genesis of blunt hepatic injuries. Most liver injuries (>85%) involve segments 6, 7, and 8 of the liver. This type of injury is believed to result from simple compression against the fixed ribs, spine, or posterior abdominal wall. Pressure through the right hemithorax may propagate through the diaphragm, causing a contusion of the dome of the right lobe of the liver. The liver's ligamentous attachment to the diaphragm and the posterior abdominal wall can act as sites of shear forces during deceleration injury. Liver injury can also result from transmission of excessively high venous pressure to remote body sites occurring at the time of impact. Liver injury occurs more easily in children than in adults because the ribs are more flexible, allowing force to be transmitted to the liver. In addition, the liver is not fully developed in children, who have a weaker connective tissue framework than do adults. A steering-column injury may cause trauma to an entire lobe of the liver.3 Deceleration injuries produce shearing forces that may tear hepatic lobes from each other and often involve the inferior vena cava and hepatic veins. Increasing numbers of central liver hematomas caused by accidents involving mountain bikes are being encountered.4 Interventional radiology procedures, such as percutaneous biopsy, cholangiography or biliary drainage, transjugular intrahepatic portosystemic shunt (TIPS) procedures, and percutaneous alcohol injection, can cause capsular tears, hematoma, bile leaks, bilomas, arteriobiliary or venobiliary fistulas, and hemoperitoneum. In the neonate, hepatic injury may be unsuspected. In neonatal fatalities, 9.6% of postmortem studies show evidence of liver trauma, especially subcapsular hematoma. Because the hepatic veins lie in rigid canals and contract poorly, the liver is incapable of achieving spontaneous hemostasis after injury. Blunt liver trauma is associated with splenic injury in 45% of patients. Rib fractures are associated with injury to the right superior aspect of the liver in 33% of patients, and duodenal and pancreatic injuries are more closely associated with hepatic left lobe trauma. Isolated liver injury occurs in less than 50% of patients.5 Liver trauma may result in the following:
Most blunt liver trauma (80% in adults, 97% in children) is currently treated conservatively. Surgical literature confirms that more than 86% of hepatic injuries have stopped bleeding at the time of surgical exploration. Conservative treatment requires the ability to clinically monitor the physiologic signs adequately and to intervene surgically if conservative treatment fails. A comparison of patients receiving operative and nonoperative treatment for liver injuries has revealed no difference in the length of hospital stay between the 2 groups, but in this study, blood transfusion requirements and intra-abdominal complications were significantly lower in the group of patients receiving conservative treatment. The liver is the most common abdominal organ injured by penetrating trauma. Penetrating trauma of the liver may be caused by bullets, shrapnel, knives, and other sharp objects. In most centers, surgery for stab wounds is performed only in patients in whom internal injury is strongly suspected. Complications from liver trauma occur in approximately 20% of patients and include delayed rupture (very rare), hemobilia, arteriovenous fistula, pseudo-aneurysm, and biloma and abscess formation. Mild hepatic injuries that involve less than 25% of 1 lobe resolve within 3 months. Most moderate injuries involving 25-50% of 1 lobe heal within 6 months, whereas severe injuries require 9-15 months to heal. Gallbladder injuries are rare. Predisposing factors for gallbladder injuries include alcohol ingestion, which increases tone of the sphincter of Oddi, and a normal, distended gallbladder. Paradoxically, patients with chronic cholecystitis are less prone to experiencing gallbladder rupture. Gallbladder injuries are classified as contusions, lacerations or perforations, and avulsions; contusions are most common. Avulsion injuries are the second most common; the gallbladder is partially or completely torn from the gallbladder fossa. Healing takes 1-15 months, and the rate of healing correlates with the severity of trauma. Several systems have been devised to classify liver injuries; however, the lack of consistency of scoring severity in organ injury is a problem. To rectify the problem, the American Association for the Surgery of Trauma (AAST) developed a system based on the amount of anatomic disruption of an individual organ. The scoring system is used routinely in the United States and includes grades 1-6. A CT scan classification of liver injuries based on the AAST liver injury criteria has been devised by Mirvis and colleagues.6 This classification has been found to be valuable in predicting prognosis and treatment needs in adult patients with liver trauma (see CT Scan). FrequencyUnited StatesLiver trauma accounts for 15-20% of blunt abdominal injuries. InternationalExact worldwide incidence of liver trauma is not known. Mortality/MorbidityAlthough blunt liver trauma accounts for 15-20% of abdominal injuries, it is responsible for more than 50% of deaths resulting from blunt abdominal trauma. The mortality rate is higher with blunt abdominal trauma than with penetrating injuries. Previously, as a result of this high mortality rate, emergency surgery was frequently indicated in patients with hepatic injury. However, with better monitoring facilities and imaging techniques, most patients with blunt abdominal trauma are now treated conservatively. SexBlunt and penetrating liver injuries are more common in males. AgeMost liver trauma occurs in adults who drive motor vehicles or engage in fighting. AnatomyFunctional (physiologic or surgical) anatomy based on hepatic vasculature is the basis of modern hepatic surgery. The nomenclature of functional anatomy is an invaluable asset for radiologists and surgeons, allowing other clinicians to define the location of liver lacerations, rupture, hematomas, and vascular complications of trauma, as well as the relationships with major vascular structures. Classic anatomic descriptions of the liver are based on hepatic vasculature. Cantlie first described the main anatomic divisions along a main plane (Cantlie line) extending from the gallbladder fossa to the inferior vena cava. This line reaches the superior surface of the liver to the right of the falciform ligament and roughly divides the liver into equal halves. Couinaud further refined the functional anatomy and demonstrated that the liver is divided into 4 sectors and 8 segments. The liver is divided by vertical and oblique planes, or scissurae, defined by the 3 main hepatic veins and a transverse plane, or transverse scissura, following a line drawn through the right and left portal branches. Hepatic veins lie between segments. The left hepatic vein divides the left side of the liver into medial and lateral segments. The middle hepatic vein divides the liver into left and right lobes. The right hepatic vein divides the right side of the liver into anterior and posterior segments. A further imaginary line (horizontal), drawn through the left and right main portal vein branches, may be used to divide the hepatic lobes into superior and inferior segments. Determining the anatomy of the liver segments allows accurate localization of hepatic masses relative to the hepatic vasculature. This localization is important because advances in liver surgery allow hemihepatectomy, as well as segmental and subsegmental resections. The 8 liver segments (namely 1, 2, 3, 4a, 4b, 5, 6, 7, 8) are numbered clockwise on the frontal view. Clinical DetailsA patient history of blunt or penetrating abdominal trauma may be forthcoming.
See also the following related eMedicine topics: Preferred Examination
See also the following related eMedicine topics: Limitations of Techniques
DIFFERENTIALSSection 3 of 12
Kidney, Trauma Spleen, Trauma Other Problems to Be ConsideredDelayed liver rupture (rare) Blunt and penetrating abdominal injuries may involve other organs, such as the spleen, kidneys, or duodenum, or the mesentery; therefore, examining other intra-abdominal organs is mandatory. RADIOGRAPHSection 4 of 12
FindingsPlain radiographic findings are nonspecific, but they are useful in evaluating rib and spinal injuries in patients with blunt abdominal trauma. Fractures of the right lower ribs should suggest the possibility of underlying liver injury. Pneumoperitoneum, major diaphragmatic injury, gross organ displacement, and metallic foreign bodies may be identified.11 Degree of ConfidencePlain radiographs are sensitive and specific in demonstrating skeletal injuries and usually are the first radiologic examination performed in patients in whom liver trauma is suspected. Radiographs may initially depict opaque foreign bodies, such as bullets or shrapnel. False Positives/NegativesBecause plain radiography is performed in a traumatized patient, an optimal-quality radiograph is not always possible. Fractures and a pneumoperitoneum may be missed. CT SCANSection 5 of 12
FindingsCT scanning, particularly contrast-enhanced CT scanning, is accurate in localizing the site and extent of liver injuries and associated trauma, providing vital information for treatment in patients.7, 8 Spiral CT scanning is the preferred scanning technique, if available. Multidetector-row CT scanning offers the further advantages of fast scanning times (allowing scanning during specific phases of intravenous contrast enhancement) and the acquisition of thin sections over a large area (allowing high-quality multiplanar reconstruction).12 CT scanning without intravenous contrast enhancement is of limited value in hepatic trauma, but it can be useful in identifying or following up a hemoperitoneum. CT scans can be used to monitor healing. Trauma to the liver may result in subcapsular or intrahepatic hematoma, contusion, vascular injury, or biliary disruption.13 CT scan criteria for staging liver trauma based on the AAST liver injury scale include the following:
CT scan findings include the following:
Degree of ConfidenceCT scanning is the mainstay of diagnosis of hepatic injuries following blunt trauma; initial CT scan findings help in determining the type of treatment required. With the use of high-speed, spiral CT scans, predicting the necessity of operative treatment or angiography is possible in patients with blunt hepatic injury before deterioration of their hemodynamic state. A finding of pooled contrast material within the peritoneal cavity indicates active and massive bleeding; patients with this finding may require emergency surgery.16 Intrahepatic pooling of contrast material with an intact liver capsule usually indicates a self-limiting hemorrhage; most patients with this finding can be treated conservatively. CT scanning has been proven to be extremely useful in helping to make therapeutic decisions in hepatic trauma and in helping to reduce laparotomy rates in as many as 70% patients at the time of initial evaluation. False Positives/NegativesFalse-positive errors in the diagnosis of liver injury with CT scans may occur as a result of beam-hardening artifacts from adjacent ribs, which can mimic contusion or hematoma. An air-contrast level within the stomach in a patient with a nasogastric tube can produce streak artifacts throughout the left lobe of the liver; these may mimic intrahepatic lacerations and/or hemorrhage. The nature of these artifacts can be confirmed if the patient is scanned in a decubitus position. False-negative findings may occur in the setting of a fatty liver only when contrast-enhanced CT scans are obtained. On these images, the enhanced fatty liver may become iso-attenuating relative to the laceration or hematoma. In this situation, a nonenhanced CT scan may provide useful information regarding hepatic injury. Focal fatty infiltration may also mimic hepatic hematoma, laceration, or infarction. Hepatic lacerations with a branching pattern can mimic nonopacified portal or hepatic veins or dilated intrahepatic bile ducts. Careful evaluation of all branching intrahepatic structures is important, and the diagnosis is made with serial images to differentiate the various structures. Small amounts of free intraperitoneal blood or fluid in the perihepatic space may mimic a subcapsular hematoma; however, these fluid collections usually do not compress the liver parenchyma. CT scans do not always help in predicting which patients require laparotomy.17 Hematomas or hemorrhage within the liver can occur with a nontraumatic etiology (see Ultrasonography). In the evaluation of recurrent hepatic bleeding, particularly after an angiographic intervention, nonenhanced and enhanced scans are important to distinguish extravasated contrast material during angiography from recurrent, ongoing hemorrhage. Other hepatic lesions that may mimic active bleeding on CT scans include calcified liver masses and hemangiomas. MRISection 6 of 12
FindingsMRI has a limited role in the evaluation of blunt abdominal trauma, and it has no advantage over CT scanning. Theoretically, MRI can be used in follow-up monitoring of patients with blunt abdominal trauma, and the modality may be useful in young and pregnant women with abdominal trauma in whom the radiation dose is a concern.18 MRCP has been used in the assessment of pancreatic duct trauma and its sequelae, and it can be used to image biliary trauma.9 Another potential use of MRI is in patients with renal failure and in patients who are allergic to radiographic contrast medium. Degree of ConfidenceMRI offers no significant advantage over CT scanning for routine evaluation of acute abdominal trauma. Experience is insufficient for assessing the value of the above-mentioned special circumstances. False Positives/NegativesSufficient experience has not been gained in the use of MRI to establish false-positive and false-negative findings. ULTRASOUNDSection 7 of 12
Findings
Degree of ConfidenceFocused assessment performed by using ultrasonography in patients with liver trauma is still investigational for evaluation of blunt and penetrating abdominal trauma.20 The primary advantage is immediate availability in emergency departments. Some centers use ultrasonography as the initial examination. Patients who are unstable and have a large amount of fluid detected on ultrasonograms are immediately transported for surgery. In addition, patients at these centers who are stable and who have a large amount of intra-abdominal fluid also may be immediately treated with surgery. An alternative approach is followed in other centers. If ultrasonographic findings are positive for intra-abdominal fluid, CT scanning is the next step. If fluid is not demonstrated on abdominal ultrasonograms, the patient is observed for 12 hours; however, if abdominal pain persists, the patient undergoes CT scanning. Ultrasonography is the initial examination of choice in the pediatric age group because of the modality's nonionizing and noninvasive nature. Ultrasonography is particularly useful in imaging neonates who are ill and in whom the clinical condition is too unstable to allow transport to a CT scanning facility but who may have a hepatic hematoma after a traumatic delivery or resuscitative efforts. In a neonate with a decreasing hematocrit level and increasing abdominal distension, ultrasonography may rapidly help in confirming a diagnosis of liver trauma. Because most children with hepatic trauma are treated conservatively, most children can be monitored by using ultrasonography.5, 21 Ultrasonography has several advantages over peritoneal lavage in the diagnosis of blunt abdominal trauma. Ultrasonography is a noninvasive procedure that is readily available at the patient's bedside and is less expensive to perform than is peritoneal lavage. However, although ultrasonography may be useful in most patients with blunt abdominal trauma, pitfalls remain. False Positives/NegativesInjury to the liver, especially at the dome or lateral segment of the left lobe of the liver, can easily be missed with ultrasonography, particularly in the presence of ileus or when pain makes the examination difficult. The sensitivity of ultrasonography in the detection of free abdominal fluid associated with bowel or mesenteric injury has been reported as only 44%. Blunt abdominal injury may involve organs other than the liver, and these injuries must be detected reliably. Ultrasonograms may not directly depict injuries to the bowel, mesentery, pancreas, diaphragm, adrenal gland, and bone. Ultrasonography is probably limited in the detection of many vascular injuries as well. A hepatic laceration may be initially difficult to detect, but it may become obvious with the passage of time. Hepatic hemorrhage may occur as a result of causes other than trauma, including sickle cell anemia, liver tumors, coagulopathies, organ phosphate toxicity, and collagen vascular disease. It may also occur in patients receiving long-term hemodialysis. Hepatic hemorrhage and rupture may occur in eclampsia, pre-eclampsia during the third trimester of pregnancy, HELLP syndrome, hepatic adenoma, and hepatocellular carcinoma. NUCLEAR MEDICINESection 8 of 12
FindingsPrior to the widespread availability of CT scanning, 99mTc sulfur colloid or 99mTc-labeled denatured red blood cell studies were widely used in the evaluation of patients with blunt hepatic and splenic trauma. The primary limitations of radionuclides are the nonspecific findings and an inability to evaluate other intraperitoneal and retroperitoneal organs. Despite the disadvantages, radionuclide techniques can offer an important imaging alternative in patients in whom CT scanning cannot be performed, such as those patients in whom the use of intravenous and oral contrast is contraindicated, those who cannot hold their breath, and those who have metallic objects or surgical clips in the abdominal cavity.
Degree of ConfidenceIn patients with blunt trauma, there is an inability to evaluate other sites of abdominal injury and to quantitate intraperitoneal and retroperitoneal hemorrhage. However, in patients in whom a bile leak or biloma is suspected, 99mTc IDA uptake imaging is the examination of choice; this provides a noninvasive technique for arriving at a specific diagnosis. False Positives/NegativesFocal defects identified with 99mTc sulfur colloid scanning or in the angiographic/hepatic phase of 99mTc IDA scanning may not be related to the trauma; these defects may instead represent simple liver cysts, granulomas, pseudotumors, abscesses, or tumors unrelated to trauma. If delayed scans are not performed, bilomas and bile leaks may be missed using 99mTc IDA scans. Delayed imaging not only provides time for the activity to accumulate within the biloma but also allows clearing of the isotope from the liver, increasing the target-to-background ratio of activity. ANGIOGRAPHYSection 9 of 12
FindingsMost patients with liver trauma who present to the emergency department in shock have positive results after peritoneal lavage and require immediate laparotomy to control hemorrhage. Angiography has no role in the evaluation of these patients. However, patients with less severe trauma may be difficult to evaluate at clinical examination and at laparotomy. If the patient is stable, cross-sectional imaging may provide sufficient detail to treat the patient conservatively. A dynamic angiographic study may demonstrate the site of active bleeding, providing an opportunity for transcatheter embolization, which may be the only treatment required. Angiographic findings in patients with liver trauma include the following:
Degree of ConfidenceEvaluating the extent of liver injury at surgery may be difficult; in fact, identifying the lesion within the liver may occasionally be impossible. Emergency hepatic angiography should be performed if at all feasible, because it not only documents the injury and helps to evaluate complications, such as pseudo-aneurysms, subcapsular hematoma, or hemobilia, it also provides access for transcatheter embolization. False Positives/NegativesAlthough angiography is useful in selected patients, false-positive and false-negative results occur in patients with hepatic trauma. Liver rupture may be spontaneous or may occur as result of liver tumors, HELLP syndrome, simple cysts, amebic abscess, and hydatid cysts. Intrahepatic arterial aneurysms may be congenital or may be related to vasculitides. INTERVENTIONSection 10 of 12
Blunt hepatic trauma more often causes venous injury and hemorrhage. Most arterial injuries are increasingly being caused by radiologic interventional procedures, such as liver biopsy, TIPS, PTC, and biliary drainage. The typical injury is a small pseudo-aneurysm, which may require meticulous, superselective angiography. A combined surgical and radiologic approach may be required in the treatment of patients with high-grade liver lacerations with injury to the retrohepatic inferior vena cava.22 Initially, the surgeon attempts to control the hemorrhage with temporary perihepatic packing. Recurrent liver parenchymal bleeding can be successfully treated by using transcatheter embolization, and bleeding from a major hepatic vein can be controlled by placing an intravenous stent.23 Embolization can be performed in persistent arterial hemorrhage, as may occur with stab wounds of the liver, and in the occlusion of pseudo-aneurysms. Transcatheter arterial embolization may reduce transfusion requirements and allow healing of hepatic injuries without surgery.24 Because hepatic arteries are not end arteries, occlusive devices should be deployed distal to the lesion to prevent collateral backdoor filling. The entire hepatic artery may be occluded, if required, as long as the portal vein is patent. If the portal vein is occluded, only selective embolization can be performed; this should prevent liver infarction due the presence of intrahepatic collaterals. The uncommon complication of bile peritonitis can be confirmed by means of diagnostic aspiration under ultrasonographic or CT scan guidance. Medical/Legal Pitfalls
See also the Medscape topic Medical Malpractice and Legal Issues. Special Concerns
MULTIMEDIASection 11 of 12
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