Drugs are an important cause of liver injury. More than 900 drugs, toxins, and herbs have been reported to cause liver injury, and drugs account for 20-40% of all instances of fulminant hepatic failure. Approximately 75% of the idiosyncratic drug reactions result in liver transplantation or death. Drug-induced hepatic injury is the most common reason cited for withdrawal of an approved drug. Physicians must be vigilant in identifying drug-related liver injury because early detection can decrease the severity of hepatotoxicity if the drug is discontinued. The manifestations of drug-induced hepatotoxicity are highly variable, ranging from asymptomatic elevation of liver enzymes to fulminant hepatic failure. Knowledge of the commonly implicated agents and a high index of suspicion are essential in diagnosis.
For excellent patient education resources, visit eMedicine's Poisoning Center, Public Health Center, and Substance Abuse Center. Also, see eMedicine's patient education articles Acetaminophen (Tylenol) Poisoning, FDA Overview, Pain Medications, and Alcoholism.
Mortality/morbidity
In the United States, approximately 2000 cases of acute liver failure occur annually and drugs account for over 50% of them (39% are due to acetaminophen, 13% are idiosyncratic reactions due to other medications). Drugs account for 2-5% of cases of patients hospitalized with jaundice and approximately 10% of all cases of acute hepatitis.
Internationally, data on the incidence of adverse hepatic drug reactions in the general population remain unknown.
Drugs withdrawn from the market secondary to hepatotoxicity
In the last few years, the US Food and Drug Administration (FDA) has withdrawn 2 drugs from the market for causing severe liver injury: bromfenac and troglitazone. Bromfenac (Duract), a nonsteroidal anti-inflammatory drug (NSAID), was introduced in 1997 as a short-term analgesic for orthopedic patients. Although approved for a dosing period of less than 10 days, patients used it for longer periods. This resulted in more than 50 cases of severe hepatic injury, and the drug had to be withdrawn in 1998. Troglitazone (Rezulin) is a thiazolidinedione and was approved in 1997 as an antidiabetic agent. Over 3 years, more than 90 cases of hepatotoxicity were reported, which resulted in withdrawal of this drug.
Kava kava, an herb used for anxiety, was reported as being hepatotoxic and was withdrawn from the German market.1 The FDA has also issued a warning in this country. This demonstrates the importance of postmarketing surveillance to identify reactions that are not reported or are underreported in drug trials.
Pemoline (Cylert), used for attention deficit disorder and narcolepsy is no longer available in the United States. The Food and Drug Administration (FDA) concluded that the overall risk of liver toxicity from pemoline outweighs the benefits. In May 2005, Abbott chose to stop sales and marketing of their brand of pemoline (Cylert) in the U.S. In October 2005, all companies that produced generic versions of pemoline also agreed to stop sales and marketing of pemoline.
Other drugs that have significant limitations of use because of their hepatotoxic effects are felbamate (Felbatol), an antiepileptic used for complex partial seizures; zileuton (Zyflo), indicated for asthma; tolcapone (Tasmar), used for Parkinson disease; trovafloxacin (Trovan), an antibiotic; benoxaprofen, an NSAID; and tienilic acid, a diuretic.
Recent warnings issued by the FDA
In June 2009, the US Food and Drug Administration (FDA) issued a report that identified 32 cases (22 adult and 10 pediatric) of serious liver injury associated with propylthiouracil (PTU). Of the adults, 12 deaths and 5 liver transplants occurred, and among the pediatric patients, 1 death and 6 liver transplants occurred. PTU is indicated for hyperthyroidism due to Graves disease.
These reports suggest an increased risk for liver toxicity with PTU compared with methimazole. Serious liver injury has been identified with methimazole in 5 cases (3 resulting in death). PTU is considered as second-line drug therapy, except in patients who are allergic or intolerant to methimazole, or for women who are in the first trimester of pregnancy. Rare cases of embryopathy, including aplasia cutis, have been reported with methimazole during pregnancy.
The FDA recommends the following criteria be considered for prescribing PTU. For more information see the FDA Safety Alert.
Reserve PTU use during first trimester of pregnancy, or in patients who are allergic to or intolerant of methimazole.
Closely monitor PTU therapy for signs and symptoms of liver injury, especially during the first 6 months after initiation of therapy.
For suspected liver injury, promptly discontinue PTU therapy and evaluate for evidence of liver injury and provide supportive care.
PTU should not be used in pediatric patients unless the patient is allergic to or intolerant of methimazole, and no other treatment options are available.
Counsel patients to promptly contact their health care provider for the following signs or symptoms: fatigue, weakness, vague abdominal pain, loss of appetite, itching, easy bruising, or yellowing of the eyes or skin.
Severe hepatic injury, including cases of hepatic failure, has been reported in patients taking interferon beta-1a (Avonex) used in treatment of multiple sclerosis. Asymptomatic elevation of hepatic transaminases have also been reported and, in some patients, recurred upon rechallenge. In some cases, these events occurred in the presence of other drugs that have been associated with hepatic injury. The potential risk of Avonex used in combination with known hepatotoxic drugs or other products (eg, alcohol) should be considered prior to Avonex administration or when adding new agents to the regimen of patients already on Avonex.
In January 2006, the US Food and Drug Administration (FDA) issued a warning after 3 cases of serious liver toxicity were reported with taking telithromycin. In June 2006, the prescribing information for telithromycin (Ketek) was changed to include a warning describing the drug's association with rare cases of serious liver injury and liver failure. Four of these events resulted in deaths and one resulted in liver transplant. The added warning follows evaluation by the FDA on postmarketing surveillance reports. If clinical hepatitis or liver enzyme elevations combined with other systemic symptoms occur, telithromycin should be permanently discontinued. Telithromycin is an antibiotic of the ketolide class, approved by the FDA in April 2004 for the treatment of respiratory infections in adults. It is marketed and is widely used in several countries including Japan and countries in Europe.
In February 2007, the FDA took further action and removed 2 of the 3 indications: acute bacterial sinusitis and acute bacterial exacerbations of chronic bronchitis. Following comprehensive scientific analysis, the FDA determined that the balance of benefits and risks no longer supports the approval of the drug for these indications. Telithromycin is now indicated for treatment of mild-to-moderate community-acquired pneumonia.
In October 2005, the manufactures of duloxetine (an anti-depressant) reported postmarketing cases of hepatitis and cholestatic jaundice. The new package insert now states, "Cymbalta should not be administered to patients with substantial alcohol use or any hepatic insufficiency."
Risk factors for drug-induced liver injury
Race: Some drugs appear to have different toxicities based on race. For example, blacks and Hispanics may be more susceptible to isoniazid (INH) toxicity. The rate of metabolism is under the control of P-450 enzymes and can vary from individual to individual.
Age: Apart from accidental exposure, hepatic drug reactions are rare in children. Elderly persons are at increased risk of hepatic injury because of decreased clearance, drug-to-drug interactions, reduced hepatic blood flow, variation in drug binding, and lower hepatic volume. In addition, poor diet, infections, and multiple hospitalizations are important reasons for drug-induced hepatotoxicity.
Sex: Although the reasons are unknown, hepatic drug reactions are more common in females.
Alcohol ingestion: Alcoholic persons are susceptible to drug toxicity because alcohol induces liver injury and cirrhotic changes that alter drug metabolism. Alcohol causes depletion of glutathione (hepatoprotective) stores that make the person more susceptible to toxicity by drugs.
Liver disease: In general, patients with chronic liver disease are not uniformly at increased risk of hepatic injury. Although the total cytochrome P-450 is reduced, some may be affected more than others. The modification of doses in persons with liver disease should be based on the knowledge of the specific enzyme involved in the metabolism. Patients with HIV infection who are co-infected with hepatitis B or C virus are at increased risk for hepatotoxic effects when treated with antiretroviral therapy. Similarly, patients with cirrhosis are at increased risk of decompensation by toxic drugs.
Genetic factors: A unique gene encodes each P-450 protein. Genetic differences in the P-450 enzymes can result in abnormal reactions to drugs, including idiosyncratic reactions. Debrisoquine is an antiarrhythmic drug that undergoes poor metabolism because of abnormal expression of P-450-II-D6. This can be identified by polymerase chain reaction amplification of mutant genes. This has led to the possibility of future detection of persons who can have abnormal reactions to a drug.
Other comorbidities: Persons with AIDS, persons who are malnourished, and persons who are fasting may be susceptible to drug reactions because of low glutathione stores.
Drug formulation: Long-acting drugs may cause more injury than shorter-acting drugs.
Host factors that may enhance susceptibility to drugs, possibly inducing liver disease
Female - Halothane, nitrofurantoin, sulindac
Male - Amoxicillin-clavulanic acid (Augmentin)
Old age - Acetaminophen, halothane, INH, amoxicillin-clavulanic acid
Young age - Salicylates, valproic acid
Fasting or malnutrition - Acetaminophen
Large body mass index/obesity - Halothane
Diabetes mellitus - Methotrexate, niacin
Renal failure - Tetracycline, allopurinol
AIDS - Dapsone, trimethoprim-sulfamethoxazole
Hepatitis C - Ibuprofen, ritonavir, flutamide
Preexisting liver disease - Niacin, tetracycline, methotrexate
Pathophysiology and mechanisms of drug-induced liver injury
Pathophysiologic mechanisms: The pathophysiologic mechanisms of hepatotoxicity are still being explored and include both hepatocellular and extracellular mechanisms. The following are some of the mechanisms that have been described:
Disruption of the hepatocyte: Covalent binding of the drug to intracellular proteins can cause a decrease in ATP levels, leading to actin disruption. Disassembly of actin fibrils at the surface of the hepatocyte causes blebs and rupture of the membrane.
Disruption of the transport proteins: Drugs that affect transport proteins at the canalicular membrane can interrupt bile flow. Loss of villous processes and interruption of transport pumps such as multidrug resistance–associated protein 3 prevent the excretion of bilirubin, causing cholestasis.
Cytolytic T-cell activation: Covalent binding of a drug to the P-450 enzyme acts as an immunogen, activating T cells and cytokines and stimulating a multifaceted immune response.
Apoptosis of hepatocytes: Activation of the apoptotic pathways by the tumor necrosis factor-alpha receptor of Fas may trigger the cascade of intercellular caspases, which results in programmed cell death.
Mitochondrial disruption: Certain drugs inhibit mitochondrial function by a dual effect on both beta-oxidation energy production by inhibiting the synthesis of nicotinamide adenine dinucleotide and flavin adenine dinucleotide, resulting in decreased ATP production.
Bile duct injury: Toxic metabolites excreted in bile may cause injury to the bile duct epithelium.
Drug toxicity mechanisms: The classic division of drug reactions is into at least 2 major groups, (1) drugs that directly affect the liver and (2) drugs that mediate an immune response.
Intrinsic or predictable drug reactions: Drugs that fall into this category cause reproducible injuries in animals, and the injury is dose related. The injury can be due to the drug itself or to a metabolite. Acetaminophen is a classic example of a known intrinsic or predictable hepatotoxin at supertherapeutic doses. Another classic example is carbon tetrachloride.
Idiosyncratic drug reactions: Idiosyncratic drug reactions can be subdivided into those that are classified as hypersensitivity or immunoallergic and those that are metabolic-idiosyncratic.
Hypersensitivity: Phenytoin is a classic, if not common, cause of hypersensitivity reactions. The response is characterized by fever, rash, and eosinophilia and is an immune-related response with a typical short latency period of 1-4 weeks.
Metabolic-idiosyncratic: This type of reaction occurs through an indirect metabolite of the offending drug. Unlike intrinsic hepatotoxins, the response rate is variable and can occur within a week or up to one year later. It occurs in a minority of patients taking the drug, and no clinical manifestations of hypersensitivity are noted. INH toxicity is considered to fall into this class. Not all drugs fall neatly into one of these categories, and overlapping mechanisms may occur with some drugs (eg, halothane).
For excellent patient education resources, visit eMedicine's Poisoning Center, Public Health Center, and Substance Abuse Center. Also, see eMedicine's patient education articles Acetaminophen (Tylenol) Poisoning, FDA Overview, Pain Medications, and Alcoholism.
Mortality/morbidity
In the United States, approximately 2000 cases of acute liver failure occur annually and drugs account for over 50% of them (39% are due to acetaminophen, 13% are idiosyncratic reactions due to other medications). Drugs account for 2-5% of cases of patients hospitalized with jaundice and approximately 10% of all cases of acute hepatitis.
Internationally, data on the incidence of adverse hepatic drug reactions in the general population remain unknown.
Drugs withdrawn from the market secondary to hepatotoxicity
In the last few years, the US Food and Drug Administration (FDA) has withdrawn 2 drugs from the market for causing severe liver injury: bromfenac and troglitazone. Bromfenac (Duract), a nonsteroidal anti-inflammatory drug (NSAID), was introduced in 1997 as a short-term analgesic for orthopedic patients. Although approved for a dosing period of less than 10 days, patients used it for longer periods. This resulted in more than 50 cases of severe hepatic injury, and the drug had to be withdrawn in 1998. Troglitazone (Rezulin) is a thiazolidinedione and was approved in 1997 as an antidiabetic agent. Over 3 years, more than 90 cases of hepatotoxicity were reported, which resulted in withdrawal of this drug.
Kava kava, an herb used for anxiety, was reported as being hepatotoxic and was withdrawn from the German market.1 The FDA has also issued a warning in this country. This demonstrates the importance of postmarketing surveillance to identify reactions that are not reported or are underreported in drug trials.
Pemoline (Cylert), used for attention deficit disorder and narcolepsy is no longer available in the United States. The Food and Drug Administration (FDA) concluded that the overall risk of liver toxicity from pemoline outweighs the benefits. In May 2005, Abbott chose to stop sales and marketing of their brand of pemoline (Cylert) in the U.S. In October 2005, all companies that produced generic versions of pemoline also agreed to stop sales and marketing of pemoline.
Other drugs that have significant limitations of use because of their hepatotoxic effects are felbamate (Felbatol), an antiepileptic used for complex partial seizures; zileuton (Zyflo), indicated for asthma; tolcapone (Tasmar), used for Parkinson disease; trovafloxacin (Trovan), an antibiotic; benoxaprofen, an NSAID; and tienilic acid, a diuretic.
Recent warnings issued by the FDA
In June 2009, the US Food and Drug Administration (FDA) issued a report that identified 32 cases (22 adult and 10 pediatric) of serious liver injury associated with propylthiouracil (PTU). Of the adults, 12 deaths and 5 liver transplants occurred, and among the pediatric patients, 1 death and 6 liver transplants occurred. PTU is indicated for hyperthyroidism due to Graves disease.
These reports suggest an increased risk for liver toxicity with PTU compared with methimazole. Serious liver injury has been identified with methimazole in 5 cases (3 resulting in death). PTU is considered as second-line drug therapy, except in patients who are allergic or intolerant to methimazole, or for women who are in the first trimester of pregnancy. Rare cases of embryopathy, including aplasia cutis, have been reported with methimazole during pregnancy.
The FDA recommends the following criteria be considered for prescribing PTU. For more information see the FDA Safety Alert.
Reserve PTU use during first trimester of pregnancy, or in patients who are allergic to or intolerant of methimazole.
Closely monitor PTU therapy for signs and symptoms of liver injury, especially during the first 6 months after initiation of therapy.
For suspected liver injury, promptly discontinue PTU therapy and evaluate for evidence of liver injury and provide supportive care.
PTU should not be used in pediatric patients unless the patient is allergic to or intolerant of methimazole, and no other treatment options are available.
Counsel patients to promptly contact their health care provider for the following signs or symptoms: fatigue, weakness, vague abdominal pain, loss of appetite, itching, easy bruising, or yellowing of the eyes or skin.
Severe hepatic injury, including cases of hepatic failure, has been reported in patients taking interferon beta-1a (Avonex) used in treatment of multiple sclerosis. Asymptomatic elevation of hepatic transaminases have also been reported and, in some patients, recurred upon rechallenge. In some cases, these events occurred in the presence of other drugs that have been associated with hepatic injury. The potential risk of Avonex used in combination with known hepatotoxic drugs or other products (eg, alcohol) should be considered prior to Avonex administration or when adding new agents to the regimen of patients already on Avonex.
In January 2006, the US Food and Drug Administration (FDA) issued a warning after 3 cases of serious liver toxicity were reported with taking telithromycin. In June 2006, the prescribing information for telithromycin (Ketek) was changed to include a warning describing the drug's association with rare cases of serious liver injury and liver failure. Four of these events resulted in deaths and one resulted in liver transplant. The added warning follows evaluation by the FDA on postmarketing surveillance reports. If clinical hepatitis or liver enzyme elevations combined with other systemic symptoms occur, telithromycin should be permanently discontinued. Telithromycin is an antibiotic of the ketolide class, approved by the FDA in April 2004 for the treatment of respiratory infections in adults. It is marketed and is widely used in several countries including Japan and countries in Europe.
In February 2007, the FDA took further action and removed 2 of the 3 indications: acute bacterial sinusitis and acute bacterial exacerbations of chronic bronchitis. Following comprehensive scientific analysis, the FDA determined that the balance of benefits and risks no longer supports the approval of the drug for these indications. Telithromycin is now indicated for treatment of mild-to-moderate community-acquired pneumonia.
In October 2005, the manufactures of duloxetine (an anti-depressant) reported postmarketing cases of hepatitis and cholestatic jaundice. The new package insert now states, "Cymbalta should not be administered to patients with substantial alcohol use or any hepatic insufficiency."
Risk factors for drug-induced liver injury
Race: Some drugs appear to have different toxicities based on race. For example, blacks and Hispanics may be more susceptible to isoniazid (INH) toxicity. The rate of metabolism is under the control of P-450 enzymes and can vary from individual to individual.
Age: Apart from accidental exposure, hepatic drug reactions are rare in children. Elderly persons are at increased risk of hepatic injury because of decreased clearance, drug-to-drug interactions, reduced hepatic blood flow, variation in drug binding, and lower hepatic volume. In addition, poor diet, infections, and multiple hospitalizations are important reasons for drug-induced hepatotoxicity.
Sex: Although the reasons are unknown, hepatic drug reactions are more common in females.
Alcohol ingestion: Alcoholic persons are susceptible to drug toxicity because alcohol induces liver injury and cirrhotic changes that alter drug metabolism. Alcohol causes depletion of glutathione (hepatoprotective) stores that make the person more susceptible to toxicity by drugs.
Liver disease: In general, patients with chronic liver disease are not uniformly at increased risk of hepatic injury. Although the total cytochrome P-450 is reduced, some may be affected more than others. The modification of doses in persons with liver disease should be based on the knowledge of the specific enzyme involved in the metabolism. Patients with HIV infection who are co-infected with hepatitis B or C virus are at increased risk for hepatotoxic effects when treated with antiretroviral therapy. Similarly, patients with cirrhosis are at increased risk of decompensation by toxic drugs.
Genetic factors: A unique gene encodes each P-450 protein. Genetic differences in the P-450 enzymes can result in abnormal reactions to drugs, including idiosyncratic reactions. Debrisoquine is an antiarrhythmic drug that undergoes poor metabolism because of abnormal expression of P-450-II-D6. This can be identified by polymerase chain reaction amplification of mutant genes. This has led to the possibility of future detection of persons who can have abnormal reactions to a drug.
Other comorbidities: Persons with AIDS, persons who are malnourished, and persons who are fasting may be susceptible to drug reactions because of low glutathione stores.
Drug formulation: Long-acting drugs may cause more injury than shorter-acting drugs.
Host factors that may enhance susceptibility to drugs, possibly inducing liver disease
Female - Halothane, nitrofurantoin, sulindac
Male - Amoxicillin-clavulanic acid (Augmentin)
Old age - Acetaminophen, halothane, INH, amoxicillin-clavulanic acid
Young age - Salicylates, valproic acid
Fasting or malnutrition - Acetaminophen
Large body mass index/obesity - Halothane
Diabetes mellitus - Methotrexate, niacin
Renal failure - Tetracycline, allopurinol
AIDS - Dapsone, trimethoprim-sulfamethoxazole
Hepatitis C - Ibuprofen, ritonavir, flutamide
Preexisting liver disease - Niacin, tetracycline, methotrexate
Pathophysiology and mechanisms of drug-induced liver injury
Pathophysiologic mechanisms: The pathophysiologic mechanisms of hepatotoxicity are still being explored and include both hepatocellular and extracellular mechanisms. The following are some of the mechanisms that have been described:
Disruption of the hepatocyte: Covalent binding of the drug to intracellular proteins can cause a decrease in ATP levels, leading to actin disruption. Disassembly of actin fibrils at the surface of the hepatocyte causes blebs and rupture of the membrane.
Disruption of the transport proteins: Drugs that affect transport proteins at the canalicular membrane can interrupt bile flow. Loss of villous processes and interruption of transport pumps such as multidrug resistance–associated protein 3 prevent the excretion of bilirubin, causing cholestasis.
Cytolytic T-cell activation: Covalent binding of a drug to the P-450 enzyme acts as an immunogen, activating T cells and cytokines and stimulating a multifaceted immune response.
Apoptosis of hepatocytes: Activation of the apoptotic pathways by the tumor necrosis factor-alpha receptor of Fas may trigger the cascade of intercellular caspases, which results in programmed cell death.
Mitochondrial disruption: Certain drugs inhibit mitochondrial function by a dual effect on both beta-oxidation energy production by inhibiting the synthesis of nicotinamide adenine dinucleotide and flavin adenine dinucleotide, resulting in decreased ATP production.
Bile duct injury: Toxic metabolites excreted in bile may cause injury to the bile duct epithelium.
Drug toxicity mechanisms: The classic division of drug reactions is into at least 2 major groups, (1) drugs that directly affect the liver and (2) drugs that mediate an immune response.
Intrinsic or predictable drug reactions: Drugs that fall into this category cause reproducible injuries in animals, and the injury is dose related. The injury can be due to the drug itself or to a metabolite. Acetaminophen is a classic example of a known intrinsic or predictable hepatotoxin at supertherapeutic doses. Another classic example is carbon tetrachloride.
Idiosyncratic drug reactions: Idiosyncratic drug reactions can be subdivided into those that are classified as hypersensitivity or immunoallergic and those that are metabolic-idiosyncratic.
Hypersensitivity: Phenytoin is a classic, if not common, cause of hypersensitivity reactions. The response is characterized by fever, rash, and eosinophilia and is an immune-related response with a typical short latency period of 1-4 weeks.
Metabolic-idiosyncratic: This type of reaction occurs through an indirect metabolite of the offending drug. Unlike intrinsic hepatotoxins, the response rate is variable and can occur within a week or up to one year later. It occurs in a minority of patients taking the drug, and no clinical manifestations of hypersensitivity are noted. INH toxicity is considered to fall into this class. Not all drugs fall neatly into one of these categories, and overlapping mechanisms may occur with some drugs (eg, halothane).
Anatomy of The Liver
The Couinaud classification of liver anatomy divides the liver into eight functionally indepedent segments.
Each segment has its own vascular inflow, outflow and biliary drainage.
In the centre of each segment there is a branch of the portal vein, hepatic artery and bile duct.
In the periphery of each segment there is vascular outflow through the hepatic veins.
Right hepatic vein divides the right lobe into anterior and posterior segments.
Middle hepatic vein divides the liver into right and left lobes (or right and left hemiliver). This plane runs from the inferior vena cava to the gallbladder fossa.
Left hepatic vein divides the left lobe into a medial and lateral part.
Portal vein divides the liver into upper and lower segments.
The left and right portal veins branch superiorly and inferiorly to project into the center of each segment.
Because of this division into self-contained units, each segment can be resected without damaging those remaining. For the liver to remain viable, resections must proceed along the vessels that define the peripheries of these segments. This means, that resection-lines parallel the hepatic veins,
The centrally located portal veins, bile ducts, and hepatic arteries are preserved.
Clockwise numbering of the segments Segments numbering
There are eight liver segments.
Segment 4 is sometimes divided into segment 4a and 4b according to Bismuth.
The numbering of the segments is in a clockwise manner (figure).
Segment 1 (caudate lobe) is located posteriorly. It is not visible on a frontal view.
On a frontal view of the liver the posteriorly located segments 6 and 7 are not visible.
The illustrations above are schematic presentations of the liversegments.
In reality however the proportions are different.
On a normal frontal view the segments 6 and 7 are not visible because they are located more posteriorly.
The right border of the liver is formed by segment 5 and 8.
Although segment 4 is part of the left hemiliver, it is situated more to the right.
Couinaud divided the liver into a functional left and right liver (in French 'gauche et droite foie') by a main portal scissurae containing the middle hepatic vein. This is known as Cantlie's line.
Cantlie's line runs from the middle of the gallbladder fossa anteriorly to the inferior vena cava posteriorly.
On this illustration it looks as if the medial part of the left lobe is separated from the lateral part by the falciform ligament. However it actually is the left hepatic vein, that separates the medial part (segment 4) from the lateral part (segments 2 and 3).
The left hepatic vein is located slightly to the left of the falciform ligament.
LEFT: above the level of the left portal vein.
RIGHT: at the level of the left portal vein Transverse anatomy
The far left figure is a transverse image through the superior liver segments, that are divided by the hepatic veins.
The right figure shows a transverse image at the level of the left portal vein.
At this level the left portal vein divides the left lobe of the liver into the superior segments (2 and 4A) and the inferior segments (3 and 4B).
The left portal vein is at a higher level than the right portal vein.
LEFT: at the level of the right portal vein.
RIGHT: at the level of the splenic vein.
The image on the far left is at the level of the right portal vein. At this level the right portal vein divides the right lobe of the liver into superior segments (7 and 8) and the inferior segments (5 and 6).
The level of the right portal vein is inferior to the level of the left portal vein.
At the level of the splenic vein, which is below the level of the right portal vein, only the inferior segments are seen (right image).
Hypertrophy of caudate lobe in a patient with livercirrhosis. Notice the small lobulated right hemiliver. Caudate lobe
The caudate lobe or segment 1 is located posteriorly.
The caudate lobe is anatomically different from other lobes in that it often has direct connections to the IVC through hepatic veins, that are separate from the main hepatic veins.
The caudate lobe may be supplied by both right and left branches of the portal vein.
On the left a patient with cirrhosis with extreme atrophy of the right lobe, normal volume of the left lobe and hypertrophy of the caudate lobe.
Due to a different blood supply the caudate lobe is spared from the disease process and hypertrophied to compensate for the loss of normal liverparenchyma
Each segment has its own vascular inflow, outflow and biliary drainage.
In the centre of each segment there is a branch of the portal vein, hepatic artery and bile duct.
In the periphery of each segment there is vascular outflow through the hepatic veins.
Right hepatic vein divides the right lobe into anterior and posterior segments.
Middle hepatic vein divides the liver into right and left lobes (or right and left hemiliver). This plane runs from the inferior vena cava to the gallbladder fossa.
Left hepatic vein divides the left lobe into a medial and lateral part.
Portal vein divides the liver into upper and lower segments.
The left and right portal veins branch superiorly and inferiorly to project into the center of each segment.
Because of this division into self-contained units, each segment can be resected without damaging those remaining. For the liver to remain viable, resections must proceed along the vessels that define the peripheries of these segments. This means, that resection-lines parallel the hepatic veins,
The centrally located portal veins, bile ducts, and hepatic arteries are preserved.
Clockwise numbering of the segments Segments numbering
There are eight liver segments.
Segment 4 is sometimes divided into segment 4a and 4b according to Bismuth.
The numbering of the segments is in a clockwise manner (figure).
Segment 1 (caudate lobe) is located posteriorly. It is not visible on a frontal view.
On a frontal view of the liver the posteriorly located segments 6 and 7 are not visible.
The illustrations above are schematic presentations of the liversegments.
In reality however the proportions are different.
On a normal frontal view the segments 6 and 7 are not visible because they are located more posteriorly.
The right border of the liver is formed by segment 5 and 8.
Although segment 4 is part of the left hemiliver, it is situated more to the right.
Couinaud divided the liver into a functional left and right liver (in French 'gauche et droite foie') by a main portal scissurae containing the middle hepatic vein. This is known as Cantlie's line.
Cantlie's line runs from the middle of the gallbladder fossa anteriorly to the inferior vena cava posteriorly.
On this illustration it looks as if the medial part of the left lobe is separated from the lateral part by the falciform ligament. However it actually is the left hepatic vein, that separates the medial part (segment 4) from the lateral part (segments 2 and 3).
The left hepatic vein is located slightly to the left of the falciform ligament.
LEFT: above the level of the left portal vein.
RIGHT: at the level of the left portal vein Transverse anatomy
The far left figure is a transverse image through the superior liver segments, that are divided by the hepatic veins.
The right figure shows a transverse image at the level of the left portal vein.
At this level the left portal vein divides the left lobe of the liver into the superior segments (2 and 4A) and the inferior segments (3 and 4B).
The left portal vein is at a higher level than the right portal vein.
LEFT: at the level of the right portal vein.
RIGHT: at the level of the splenic vein.
The image on the far left is at the level of the right portal vein. At this level the right portal vein divides the right lobe of the liver into superior segments (7 and 8) and the inferior segments (5 and 6).
The level of the right portal vein is inferior to the level of the left portal vein.
At the level of the splenic vein, which is below the level of the right portal vein, only the inferior segments are seen (right image).
Hypertrophy of caudate lobe in a patient with livercirrhosis. Notice the small lobulated right hemiliver. Caudate lobe
The caudate lobe or segment 1 is located posteriorly.
The caudate lobe is anatomically different from other lobes in that it often has direct connections to the IVC through hepatic veins, that are separate from the main hepatic veins.
The caudate lobe may be supplied by both right and left branches of the portal vein.
On the left a patient with cirrhosis with extreme atrophy of the right lobe, normal volume of the left lobe and hypertrophy of the caudate lobe.
Due to a different blood supply the caudate lobe is spared from the disease process and hypertrophied to compensate for the loss of normal liverparenchyma
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