Principles of surgery

PART II
Specific Considerations

CHAPTER 31
Liver

BASIC SCIENCE QUESTIONS

1. What is the average weight of an adult liver?

A. 700 g

B. 1100 g

C. 1500 g

D. 1900 g

Answer: C

The liver is the largest [intestinal] organ in the body, weighing approximately 1500 g. (See Schwartz 9th ed., p 1094.)

2. The falciform ligament divides

A. Segments I and II

B. Segments III and IV

C. Segments V and VI

D. Segments VII and VIII

Answer: B

The round ligament is the remnant of the obliterated umbilical vein and enters the left liver hilum at the front edge of the falciform ligament. The falciform ligament separates the left lateral and left medial segments along the umbilical fissure and anchors the liver to the anterior abdominal wall.

Couinaud divided the liver into eight segments, numbering them in a clockwise direction beginning with the caudate lobe as segment I. Segments II and III comprise the left lateral segment, and segment IV is the left medial segment. Thus, the left lobe is made up of the left lateral segment (Couinaud’s segments II and III) and the left medial segment (segment IV). Segment IV can be subdivided into segment IVB and segment IVA. Segment IVA is cephalad and just below the diaphragm, spanning from segment VIII to the falciform ligament adjacent to segment II. Segment IVB is caudad and adjacent to the gallbladder fossa. The right lobe is comprised of segments V, VI, VII, and VIII, with segments V and VIII making up the right anterior lobe, and segments VI and VII the right posterior lobe. (See Schwartz 9th ed., p 1095, and Fig. 31-1.)

Image

FIG. 31-1. A. Hepatic ligaments suspending the liver to the diaphragm and anterior abdominal wall. B. Couinaud’s liver segments (I through VIII) numbered in a clockwise manner. The left lobe includes segments II to IV, the right lobe includes segments V to VIII, and the caudate lobe is segment I. IVC = inferior vena cava.

3. Approximately what percentage of the blood supply to the liver is provided by the hepatic artery?

A. 10%

B. 25%

C. 50%

D. 75%

Answer: B

The liver has a dual blood supply consisting of the hepatic artery and the portal vein. The hepatic artery delivers approximately 25% of the blood supply, and the portal vein approximately 75%. (See Schwartz 9th ed., p 1096.)

4. The hepatic artery usually arises from the celiac trunk and divides into the right and left hepatic artery after giving off the gastroduodenal artery. Which of the following is the most common variant of this normal anatomy?

A. More proximal bifurcation of the common hepatic artery (near the celiac) into right and left hepatic arteries

B. More distal bifurcation of the common hepatic artery (near the liver) into right and left hepatic arteries

C. Replaced right hepatic artery (origin from the SMA)

D. Replaced left hepatic artery (origin from the SMA)

Answer: C

The hepatic artery arises from the celiac axis (trunk), which gives off the left gastric, splenic, and common hepatic arteries (Fig. 31-2). The common hepatic artery then divides into the gastroduodenal artery and the hepatic artery proper. The right gastric artery typically originates off of the hepatic artery proper, but this is variable. The hepatic artery proper divides into the right and left hepatic arteries. This ‘classic’ or standard arterial anatomy is present in only approximately 75% of cases, with the remaining 25% having variable anatomy.

The most common hepatic arterial variants are shown (Fig. 31-3). The right hepatic artery is replaced coming off the superior mesenteric artery (SMA) 18 to 22% of the time. When there is a replacement or accessory right hepatic artery, it traverses posterior to the portal vein and then takes up a right lateral position before diving into the liver parenchyma. (See Schwartz 9th ed., p 1096.)

Image

FIG. 31-2. Arterial anatomy of the upper abdomen and liver, including the celiac trunk and hepatic artery branches. a. = artery; LHA = left hepatic artery; RHA = right hepatic artery.

Image

FIG. 31-3. Common hepatic artery anatomic variants. SMA = superior mesenteric artery.

5. The right hepatic vein drains

A. Segment I only

B. Segment II-III

C. Segment V-VIII

D. Segment VIII only

Answer: C

There are three hepatic veins (right, middle, and left) that pass obliquely through the liver to drain the blood to the suprahepatic IVC and eventually the right atrium (Fig. 31-4). The right hepatic vein drains segments V to VIII; the middle hepatic vein drains segment IV as well as segments V and VIII; and the left hepatic vein drains segments II and III. The caudate lobe [segment I] is unique because its venous drainage feeds directly into the IVC. (See Schwartz 9th ed., p 1098.)

Image

FIG. 31-4. Confluence of the three hepatic veins (HVs) and the inferior vena cava (IVC). Note that the middle and left hepatic veins (HVs) drain into a common trunk before entering the IVC. a. = artery; v. = vein. (Adapted with permission from Cameron JL (ed): Atlas of Surgery. Vol. I, Gallbladder and Biliary Tract, the Liver, Portasystemic Shunts, the Pancreas. Toronto: BC Decker, 1990, p 153.)

6. Bile acids produced in the liver are conjugated to which of the following amino acids before secretion in the bile?

A. Alanine

B. Glycine

C. Tryptophan

D. Valine

Answer: B

Bile salts, in conjunction with phospholipids, are responsible for the digestion and absorption of lipids in the small intestine. Bile salts are sodium and potassium salts of bile acids conjugated to amino acids. The bile acids are derivatives of cholesterol synthesized in the hepatocyte. Cholesterol, ingested from the diet or derived from hepatic synthesis, is converted into the bile acids cholic acid and chenodeoxycholic acid. These bile acids are conjugated to either glycine or taurine before secretion into the biliary system. Bacteria in the intestine can remove glycine and taurine from bile salts. They can also convert some of the primary bile acids into secondary bile acids by removing a hydroxyl group, producing deoxycholic from cholic acid, and lithocholic from chenodeoxycholic acid. (See Schwartz 9th ed., p 1100.)

7. Acetaminophen overdose causes liver damage by

A. Creation of a toxic metabolite by the cytochrome P-450 system

B. Creation of a toxic metabolite by conjugation

C. Direct injury to the cell membrane of the hepatocyte

D. Direct injury to the mitochondria of the hepatocyte

Answer: A

There are two main reactions that can occur in the liver important for drug metabolism. Phase I reactions include oxidation, reduction, and hydrolysis of molecules that result in metabolites that are more hydrophilic than the original chemicals. The cytochrome P-450 system is a family of hemoproteins important for oxidative reactions involving drug and toxic substances. Phase II reactions, also known asconjugation reactions, are synthetic reactions that involve addition of subgroups to the drug molecule. These subgroups include glucuronate, acetate, glutathione, glycine, sulfate, and methyl groups.

It is important to note that some drugs may be converted to active products by metabolism in the liver. An example is acetaminophen when taken in larger doses. Normally, acetaminophen is conjugated by the liver to harmless glucuronide and sulfate metabolites that are water soluble and eliminated in the urine. During an overdose, the normal metabolic pathways are overwhelmed, and some of the drug is converted to a reactive and toxic intermediate by the cytochrome P-450 system. Glutathione can normally bind to this intermediate and lead to the excretion of a harmless product. However, as glutathione stores are diminished, the reactive intermediate cannot be detoxified and it combines with lipid bilayers of hepatocytes, which results in cellular necrosis. Thus, treatment of acetaminophen overdoses consists of replacing glutathione with sulfhydryl compounds such as acetylcysteine. (See Schwartz 9th ed., p 1100.)

8. Which of the following is an acute phase protein?

A. Albumin

B. Pre-albumin

C. Transferrin

D. Ceruloplasmin

Answer: D

The liver is the site of synthesis of acute phase proteins that consist of a group of plasma proteins that are rapidly released in response to inflammatory conditions elsewhere in the body. The synthesis of these proteins in the liver is influenced by a number of inflammatory mediators. Cytokines such as tumor necrosis factor alpha (TNF-α), interferon-γ, interleukin-1 (IL-1), inter-leukin-6 (IL-6), and interleukin-8 (IL-8) are released by inflammatory cells into the circulation at sites of injury and modulate the acute phase response. In response to these cytokines, the liver increases synthesis and release of a wide variety of proteins, including ceruloplasmin, complement factors, C-reactive protein, D-dimer protein, alpha1-antitrysin, and serum amyloid A. There are proteins such as serum albumin and transferring whose levels also decrease (negative acute phase proteins) in response to inflammation. (See Schwartz 9th ed., p 1102.)

9. Which hepatic cells provides the primary defense against lipopolysaccharide (LPS)?

A. Hepatocytes

B. Kupffer cells

C. Bile duct epithelial cells

D. Intrahepatic endothelial cells

Answer: B

The complications of gram-negative sepsis are initiated by endotoxin (lipopolysaccharide, or LPS). LPS is a glycolipid constituent of the outer membranes of gram-negative bacteria composed of a hydrophilic polysaccharide portion and a hydrophobic domain called lipid A. The lipid A structure is the LPS component responsible for the biologic effects of LPS. Mere nanogram amounts of LPS injected into humans can result in the manifestations of septic shock. The profound effects of LPS are caused not only by the direct effect of LPS itself but also by activation of LPS-sensitive cells, which results in the excessive release of cytokines and other inflammatory mediators.

The liver is the main organ involved in the clearance of LPS from the bloodstream and so plays a critical role in the identification and processing of LPS. Kupffer cells are the resident macrophages of the liver and have been shown to participate in LPS clearance. Studies have demonstrated that the majority of radiolabeled LPS injected IV is quickly cleared from the circulation and found in the liver, primarily localized to the Kupffer cells. Kupffer cells also contribute to the inflammatory cascade by producing cytokines in response to LPS. Interestingly, hepatocytes, the parenchymal cells of the liver, also have all the components required for LPS recognition and signaling and can participate in the response to LPS and process LPS for clearance. (See Schwartz 9th ed., p 1102.)

10. Heme is broken down by heme oxygenase to three products of metabolism. Which of the following is one of those three products of metabolism?

A. Ferrous sulfate

B. Carbon monoxide

C. Conjugated bilirubin

D. Ferritin

Answer: B

Heme oxygenase (HO) is the rate-limiting enzyme in the degradation of heme to yield biliverdin, carbon monoxide (CO), and free iron (Fig. 31-5). The HO system, which is activated in response to multiple cellular stresses, has been shown to be an endogenous cytoprotectant in a variety of inflammatory conditions. Currently three HO isozymes have been identified. HO-1 is the inducible form of HO, whereas HO-2 and HO-3 are constitutively expressed. The function of HO in heme degradation is essential due to the potentially toxic effects of heme. An excess of heme can cause cellular damage from oxidative stress due to its production of reactive oxygen species. Thus, the HO system is an important defense mechanism against free heme-mediated oxidative stress. (See Schwartz 9th ed., p 1104.)

Image

FIG. 31-5. Heme oxygenase 1 (HO-1) and carbon monoxide (CO) signaling. HO-1 is an enzyme involved in the degradation of heme. Its protective effects in settings of hepatic stress are mediated by the catalytic products of heme degradation: ferritin, bilirubin, and CO.

11. The primary function of toll-like receptors is

A. Vasodilation

B. Removal of oxygen free radicals

C. Activation of the immune system

D. Regulation of the calcium channel

Answer: C

The liver is a central regulator of the systemic immune response after acute insults to the body. Not only does it play a crucial role in modulating the systemic inflammatory response to infection or injury, it is also subject to injury and dysfunction from these same processes. Recent advances in the study of mechanisms for the activation of the innate immune system have pointed to the TLRs as a common pathway for immune recognition of microbial invasion and tissue injury. By recognizing either microbial products or endogenous molecules released from damaged sites, the TLR system is capable of alerting the host to danger by activating the innate immune system. (See Schwartz 9th ed., p 1105.)

12. Portosystemic shunts can occur in

A. The rectum

B. The pancreas

C. The falciform ligament

D. None of the above

Answer: C

The portal venous system is without valves and drains blood from the spleen, pancreas, gallbladder, and abdominal portion of the alimentary tract into the liver. Tributaries of the portal vein communicate with veins draining directly into the systemic circulation. These communications occur at the gastroesophageal junction, anal canal, falciform ligament, splenic venous bed and left renal vein, and retroperitoneum (Fig. 31-6). The normal portal venous pressure is 5 to 10 mmHg, and at this pressure very little blood is shunted from the portal venous system into the systemic circulation. As portal venous pressure increases, however, the communications with the systemic circulation dilate, and a large amount of blood may be shunted around the liver and into the systemic circulation. (See Schwartz 9th ed., p 1111.)

Image

FIG. 31-6. Intra-abdominal venous flow pathways leading to engorged veins (varices) from portal hypertension. 1, Coronary vein; 2, superior hemorrhoidal veins; 3, paraumbilical veins; 4, Retzius’ veins; 5, veins of Sappey; A, portal vein; B, splenic vein; C, superior mesenteric vein; D, inferior mesenteric vein; E, inferior vena cava; F, superior vena cava; G, hepatic veins; a, esophageal veins; a1, azygos system; b, vasa brevia; c, middle and inferior hemorrhoidal veins; d, intestinal; e, epigastric veins.

13. The most common gene mutation in adult polycystic liver disease is in which of the following genes?

A. Polycystic kidney disease gene

B. Bilirubin UDP-glucuronosyltransferase

C. Alpha1-antitrypsin

D. ATP7B

Answer: A

Adult polycystic liver disease (ADPCLD) occurs as an autosomal dominant disease and usually presents in the third decade of life. Some 44 to 76% of affected families are found to have mutations of PKD1 and approximately 75% have mutations of PKD2.

Mutations in bilirubin UDP-glucuronosyltransferase are associated with Gilbert syndrome and Crigler-Najjar syndrome. Mutation in ATP7B cause’s Wilson’s disease.

Mutations in alpha1-antitrypsin cause alpha1-antitrypsin deficiency. (See Schwartz 9th ed., p 1119.)

CLINICAL QUESTIONS

1. Which of the following laboratory test is most specific for liver disease?

A. AST

B. ALT

C. Alkaline phosphatase

D. Albumin

Answer: B

Hepatocellular injury of the liver is usually indicated by abnormalities in levels of the liver aminotransferases AST and ALT. These enzymes participate in gluconeogenesis by catalyzing the transfer of amino groups from aspartic acid or alanine to ketoglutaric acid to produce oxaloacetic acid and pyruvic acid, respectively (these enzymes were formerly referred to as glutamic-oxaloacetic transaminaseand glutamic-pyruvic transaminase). AST is found in the liver, cardiac muscle, skeletal muscle, kidney, brain, pancreas, lungs, and red blood cells and thus is less specific for disorders of the liver. ALT is predominately found in the liver and thus is more specific for liver disease.

Alkaline phosphatase is present in bone and kidney as well as the liver.

Albumin synthesis is an important function of the liver and thus can be measured to evaluate the liver’s synthetic function. The liver produces approximately 10 g of albumin per day. However, albumin levels are dependent on a number of factors such as nutritional status, renal dysfunction, protein-losing enteropathies, and hormonal disturbances. In addition, level of albumin is not a marker of acute hepatic dysfunction due to albumin’s long half-life of 15 to 20 days. (See Schwartz 9th ed., p 1101.)

2. Which of the following would be a likely cause of indirect hyperbilirubinemia?

A. Biliary atresia

B. Pancreatic cancer

C. Mirizzi’s syndrome

D. Resorption of a large hematoma

Answer: D

Bilirubin is a breakdown product of hemoglobin metabolism. Unconjugated bilirubin is insoluble and thus is transported to the liver bound to albumin. In the liver, it is conjugated to allow excretion in bile. Measured total bilirubin levels can be low, normal, or high in patients with significant liver disease because of the liver’s reserve ability to conjugate significant amounts of bilirubin. Thus, to help aid in the diagnosis of hyperbilirubinemia, fractionation of the total bilirubin is usually performed to distinguish between conjugated (direct) and unconjugated (indirect) bilirubin. Indirect bilirubin is a term frequently used to refer to unconjugated bilirubin in the circulation because the addition of another chemical is necessary to differentiate this fraction from the whole. Normally, >90% of serum bilirubin is unconjugated. The testing process for conjugated bilirubin, in contrast, is direct without the addition of other agents. The direct bilirubin test measures the levels of conjugated bilirubin and delta bilirubin (conjugated bilirubin bound to albumin). The patterns of elevation of the different fractions of bilirubin provide important diagnostic clues as to the cause of cholestasis. In general, an elevated indirect bilirubin level suggests intrahepatic cholestasis and an elevated direct bilirubin level suggests extrahepatic obstruction. Mechanisms that can result in increases in unconjugated bilirubin levels include increased bilirubin production (hemolytic disorders and resorption of hematomas) or defects (inherited or acquired) in hepatic uptake or conjugation. The rate-limiting step in bilirubin metabolism is the excretion of bilirubin from hepatocytes, so conjugated hyperbilirubinemia can be seen in inherited or acquired disorders of intrahepatic excretion or extrahepatic obstruction.

Biliary atresia, pancreatic cancer, and Mirizzi’s syndrome all cause obstruction of the biliary system, which will result in conjugated (direct) hyperbilirubinemia. (See Schwartz 9th ed., p 1100.)

3. A patient with Gilbert syndrome presents to the ER with a mild flu-like illness and a bilirubin of 5.2. The most appropriate treatment is

A. Discharge home, no treatment is needed

B. IV hydration only

C. IV hydration, transfusion for Hg 10 g/dL

D. Plasmapheresis

Answer: A

Gilbert syndrome is a genetic variant characterized by diminished activity of the enzyme glucuronyltransferase, which results in decreased conjugation of bilirubin to glucuronide. It is a benign condition that affects approximately 4 to 7% of the population. Typically, the disease results in transient mild increases in unconjugated bilirubin levels and jaundice during episodes of fasting, stress, or illness. These episodes are self limited and usually do not require further treatment. (See Schwartz 9th ed., p 1102.)

4. The most common cause of acute liver failure (ALF) in the United States is

A. Hepatitis C

B. Hepatitis B

C. Drug ingestion

D. Trauma

Answer: C

Acute liver failure (ALF) occurs when the rate and extent of hepatocyte death exceeds the liver’s regenerative capabilities. It was initially described as a specific disease entity in the 1950s. It also has been referred to as fulminant hepatic failure. ALF is a rare disorder affecting approximately 2000 patients annually in the United States.

In the East and developing portions of the world, the most common causes of ALF are viral infections, primarily hepatitis B, A, and E. In these areas there are a relatively small number of drug-induced cases. In contrast, 65% of cases of ALF in the West are thought to be due to drugs and toxins, with acetaminophen (paracetamol) being the most common etiologic agent in the United States, Australia, United Kingdom, and most of Europe. It is interesting that in France and Spain, where acetaminophen sales are restricted, the rate of acetaminophen-induced ALF is quite low. Acetaminophen-induced ALF is also uncommon in South America. The U.S. Acute Liver Failure Study Group identified several other causes of ALF, including autoimmune hepatitis, hypoperfusion of the liver (in cardiomyopathy or cardiogenic shock), pregnancy-related conditions, and Wilson’s disease. Even with exhaustive efforts to identify a cause, approximately 20% of all cases of ALF remain indeterminate in origin.

If acetaminophen overdose is suspected to have occurred within a few hours of presentation, administration of activated charcoal may be useful to reduce the volume of acetaminophen present in the GI tract. N-acetylcysteine (NAC), the clinically effective antidote for acetaminophen overdose, should be administered as early as possible to any patient with suspected acetaminophen-associated ALF. NAC also should be administered to patients with ALF of unclear etiology, because glutathione stabilization may be beneficial in this patient population as well. (See Schwartz 9th ed., p 1107.)

5. Which of the following may be associated with improved prognosis for a patient with acute liver failure?

A. Hypophosphatemia

B. Hyperkalemia

C. Hypokalemia

D. Hypernatremia

Answer: A

The majority of patients with ALF need to be monitored in the intensive care unit (ICU) setting, and specific attention needs to be given to fluid management, ulcer prophylaxis, hemodynamic monitoring, electrolyte management, and surveillance for and treatment of infection. Surveillance cultures should be performed to identify bacterial and fungal infections as early as possible. Serum phosphorus levels need to be monitored. Hypophosphatemia, which may indicate a higher likelihood of spontaneous recovery, needs to be corrected via IV administration of phosphorus. (See Schwartz 9th ed., p 1108.)

6. A patient with cirrhosis requires an elective segmental colon resection for a benign polyp. His bilirubin is 2.3, albumin is 2.4, and INR is 1.8 and he has no ascites or encephalopathy. His risk of dying from his colon resection is approximately

A. 10%

B. 30%

C. 50%

D. 80%

Answer: B

The Child-Turcotte-Pugh (CTP) score was originally developed to evaluate the risk of portocaval shunt procedures secondary to portal hypertension and subsequently has been shown to be useful in predicting surgical risks of other intra-abdominal operations performed on cirrhotic patients (Table 31-1). Numerous studies have demonstrated overall surgical mortality rates of 10% for patients with class A cirrhosis, 30% for those with class B cirrhosis, and 75 to 80% for those with class C cirrhosis.

This patient has a Child-Turcotte-Pugh score of 2 (bilirubin 2-3 mg/dL) + 3 (albumin 2.8 g/dL) + 2 (INR 1.7-2.2) = 7, which makes him a class B cirrhotic. (See Schwartz 9th ed., p 1111.)

TABLE 31-1 Child-Turcotte-Pugh (CTP) score

Image

7. The MELD score is calculated using

A. Bilirubin, creatinine, INR

B. Bilirubin, INR, ascites

C. INR, ascites, encephalopathy

D. None of the above

Answer: A

The Model for End-Stage Liver Disease (MELD) is a linear regression model based on objective laboratory values (INR, bilirubin level, and creatinine level). It was originally developed as a tool to predict mortality after transjugular intrahepatic portosystemic shunt (TIPS) but has been validated and has been used as the sole method of liver transplant allocation in the United States since 2002. The MELD formula is as follows: MELD score = 10 [0.957 Ln(SCr) + 0.378 Ln(Tbil) + 1.12 Ln(INR) + 0.643] where SCr is serum creatinine level (in milligrams per deciliter) and Tbil is serum bilirubin level (in milligrams per deciliter). (See Schwartz 9th ed., p 1111.)

8. Portal hypertension is defined as

A. Wedged hepatic venous pressure >10 mmHg

B. Splenic pressure >15 mmHg

C. Wedged hepatic venous pressure >20 mmHg

D. venous pressure (measured at surgery) >25 mmHg

Answer: B

The most accurate method of determining portal hypertension is hepatic venography. The most commonly used procedure involves placing a balloon catheter directly into the hepatic vein and measuring the free hepatic venous pressure (FHVP) with the balloon deflated and the wedged hepatic venous pressure (WHVP) with the balloon inflated to occlude the hepatic vein. The hepatic venous pressure gradient (HVPG) is then calculated by subtracting the free from the wedged venous pressure (HVPG = WHVP – FHVP). The HVPG represents the pressure in the hepatic sinusoids and portal vein and is a measure of portal venous pressure.

A WHVP or direct portal venous pressure that is >5 mmHg greater than the inferior vena cava (IVC) pressure, a splenic pressure of >15 mmHg, or a portal venous pressure measured at surgery of >20 mmHg is abnormal and indicates portal hypertension. A portal pressure of >12 mmHg is necessary for varices to form and subsequently bleed. (See Schwartz 9th ed., p 1112.)

9. Myeloproliferative disorders cause portal hypertension that is

A. Presinusoidal (extrahepatic)

B. Presinusoidal (intrahepatic)

C. Intrahepatic

D. Postsinusoidal

Answer: B

The causes of portal hypertension can be divided into three major groups: presinusoidal, sinusoidal, and postsinusoidal. Although multiple disease processes can result in portal hypertension (Table 31-2), in the United States the most common cause of portal hypertension is usually an intrahepatic one, namely, cirrhosis. (See Schwartz 9th ed., p 1112.)

TABLE 31-2 Etiology of portal hypertension

Presinusoidal

Sinistral/extrahepatic

Splenic vein thrombosis

Splenomegaly

Splenic arteriovenous fistula

Intrahepatic

Schistosomiasis

Congenital hepatic fibrosis

Nodular regenerative hyperplasia

Idiopathic portal fibrosis

Myeloproliferative disorder

Sarcoid

Graft-versus-host disease

Sinusoidal

Intrahepatic

Cirrhosis

Viral infection

Alcohol abuse

Primary biliary cirrhosis

Autoimmune hepatitis

Primary sclerosing cholangitis

Metabolic abnormality

Postsinusoidal

Intrahepatic

Vascular occlusive disease

Posthepatic

Budd-Chiari syndrome

Congestive heart failure

Inferior vena caval web

Constrictive pericarditis

10. A patient with Child’s B cirrhosis is admitted to the ICU with a massive acute variceal bleed. Initial orders should include

A. Factor VIIa

B. Transfusion of packed red blood cells (PRBCs) for Hg 12 g

C. Ceftriaxone

D. Dopamine tritrated to keep systolic BP ≥100 mmHg

Answer: C

The most significant manifestation of portal hypertension and the leading cause of morbidity and mortality associated with portal hypertension is variceal bleeding. Approximately 30% of patients with compensated cirrhosis and 60% of patients with decompensated cirrhosis have esophageal varices. One third of all patients with varices experience variceal bleeding. Each episode of bleeding is associated with a 20 to 30% risk of mortality. Seventy percent of patients who survive the initial bleed will experience recurrent variceal hemorrhage within 1 year if left untreated.

Patients with acute variceal hemorrhage should be admitted to an ICU for resuscitation and management. Blood resuscitation should be performed carefully to a hemoglobin level of approximately 8 g/dL. Over replacement of packed red blood cells and the overzealous administration of saline can lead to both rebleeding and increased mortality. Administration of fresh-frozen plasma and platelets can be considered in patients with severe coagulopathy. Use of recombinant factor VIIa has not been shown to be more beneficial than standard therapy and therefore is not recommended at this time. Cirrhotic patients with variceal bleeding have a high risk of developing bacterial infections, which are associated with rebleeding and a higher mortality rate. The use of short-term prophylactic antibiotics has been shown both to decrease the rate of bacterial infections and to increase survival. Therefore, their use is recommended, and ceftriaxone 1 g/day IV is often given. Pharmacologic therapy for the variceal hemorrhage can be initiated as soon as the diagnosis of variceal bleeding is made. Vasopressin, administered IV at a dose of 0.2 to 0.8 units/min, is the most potent vasoconstrictor. However, its use is limited by its large number of side effects, and it should be administered for only a short period of time at high doses to prevent ischemic complications. Somatostatin and its analogue octreotide (initial bolus of 50 μg IV followed by continuous infusion of 50 μg/h) also cause splanchnic vasoconstriction. Octreotide has the advantage that it can be administered for 5 days or longer, and it is currently the preferred pharmacologic agent for initial management of acute variceal bleeding. In addition to pharmacologic therapy EGD should be carried out as soon as possible and EVL should be performed. This combination of pharmacologic and EVL therapy has been shown both to improve the initial control of bleeding and to increase the 5-day hemostasis rate. (See Schwartz 9th ed., p 1113.)

11. The best initial therapy for bleeding greater curve (gastric) varices in a patient with a patent splenic vein is

A. Embolism of the splenic vein

B. Splenectomy

C. Endoscopic variceal ablation

D. Splenorenal shunt

Answer: C

Gastric varices that occur along the lesser curvature of the stomach should be considered an extension of the patient’s esophageal varices and treated in a manner similar to esophageal varices. Gastric varices along the greater curvature, however, require the evaluation of the splenic vein to assure patency. In the presence of cirrhosis and a patent splenic vein, greater curvature gastric varices can be managed with gastric variceal obturation using N-butyl-cyanoacrylate if available. If gastric variceal obturation is unavailable or if endoscopic therapy fails, the patient should be considered for TIPS, which will control variceal bleeding in >90% of cases. (See Schwartz 9th ed., p 1113.)

12. Initial therapy for primary Budd-Chiari syndrome is

A. Anticoagulation

B. Symptomatic control of bleeding varices

C. TIPS

D. Portocaval shunt

Answer: A

Budd-Chiari syndrome (BCS) is an uncommon congestive hepatopathy characterized by the obstruction of hepatic venous outflow. Patients may present with acute signs and symptoms of abdominal pain, scites, and hepatomegaly or more chronic symptoms related to long-standing portal hypertension.

BCS is defined as primary when the obstructive process involves an endoluminal venous thrombosis. BCS is considered as a secondary process when the veins are compressed or invaded by a neighboring lesion originating outside the vein. A thorough evaluation demonstrates one or more thrombotic risk factors in approximately 75 to 90% of patients with primary BCS. Twenty-five percent of primary BCS patients have two or more risk factors. BCS remains poorly understood, however, and primary myeloproliferative disorders account for approximately 35 to 50% of the primary cases of BCS.

Initial treatment consists of diagnosing and medically managing the underlying disease process and preventing extension of the hepatic vein thrombosis through systemic anticoagulation. The BCS-associated portal hypertension and ascites are medically managed in a manner similar to that in most cirrhotic patients. Thrombolytic therapy alone for acute thrombosis may be attempted. However, the risk:benefit ratio is still unknown. Hepatic decompression aims to decrease sinusoidal pressure by restoring the outflow of blood from the liver via either medical therapy, recanalization of the obstructed hepatic veins, or side-to-side portacaval shunt. Radiographic and surgical intervention should be reserved for those patients whose condition is nonresponsive to medical therapy. (See Schwartz 9th ed., p 1114.)

13. The most common organism isolated from hepatic abscesses is

A. Escherichia coli

B. Bacteroides fragilis

C. Staphyloccus aureus

D. Group A Streptococcus

Answer: A

Approximately 40% of abscesses are monomicrobial, an additional 40% are polymicrobial, and 20% are culture negative. The most common infecting agents are gram-negative organisms. Escherichia coli is found in two thirds, and Streptococcus faecalisKlebsiella, and Proteus vulgaris are also common. Anaerobic organisms such as Bacteroides fragilis are also seen frequently. Staphylococcus andStreptococcus are more common in patients with endocarditis and infected indwelling catheters. (See Schwartz 9th ed., p 1115.)

14. Which of the following is considered the current standard treatment of a 5 cm pyogenic abscess of the right hepatic lobe?

A. Percutaneous aspiration

B. Percutaneous drainage

C. Laparoscopic drainage

D. Open surgical drainage

Answer: A

The current cornerstones of treatment include correction of the underlying cause, needle aspiration, and IV antibiotic therapy. On presentation, percutaneous aspiration and culture of the aspirate may be beneficial to guide subsequent antibiotic therapy. Initial antibiotic therapy needs to cover gram-negative as well as anaerobic organisms. Aspiration and placement of a drainage catheter is beneficial for only a minority of pyogenic abscesses, because most are quite viscous and drainage is ineffective. Antibiotic therapy must be continued for at least 8 weeks. Aspiration and IV antibiotic therapy can be expected to be effective in 80 to 90% of patients. If this initial mode of therapy fails, the patients should undergo surgical therapy, including laparoscopic or open drainage. Anatomic surgical resection can be performed in patients with recalcitrant abscesses. (See Schwartz 9th ed., p 1115.)

15. Which of the following empiric medications should be added for patients with a liver abscess who have traveled extensively in South America?

A. Metronidazole

B. Albendazole

C. Piperazine citrate

D. Mebendazole

Answer: A

Entamoeba histolytica is a parasite that is endemic worldwide, infecting approximately 10% of the world’s population. Amebiasis is most common in subtropical climates, especially in areas with poor sanitation. Amebiasis should be considered in patients who have traveled to an endemic area and present with right upper quadrant pain, fever, hepatomegaly, and hepatic abscess. Even though this disease process is secondary to a colonic infection, the presence of diarrhea is unusual. For most patients findings of the fluorescent antibody test for E. histolytica are positive, and results can remain positive for some time after a clinical cure. Amebiasis is unlikely to be present if the serologic test results are negative.

Metronidazole 750 mg tid for 7 to 10 days is the treatment of choice and is successful in 95% of cases. Defervescence usually occurs in 3 to 5 days. The time necessary for the abscess to resolve depends on the initial size at presentation and varies from 30 to 300 days.

Hydatid disease is most common in sheep-raising areas, where dogs have access to infected offal. These include South Australia, New Zealand, Africa, Greece, Spain, and the Middle East. The diagnosis of hydatid disease is based on the findings of an enzyme-linked immunosorbent assay (ELISA) for echinococcal antigens, and results are positive in approximately 85% of infected patients. The ELISA results may be negative in an infected patient if the cyst has not leaked or does not contain scolices, or if the parasite is no longer viable. Eosinophilia of >7% is found is approximately 30% of infected patients. Ultrasonography and CT scanning of the abdomen are both quite sensitive for detecting hydatid cysts. The appearance of the cysts on images depends on the stage of cyst development. Typically, hydatid cysts are well-defined hypodense lesions with a distinct wall. Ring-like calcifications of the pericysts are present in 20 to 30% of cases. As healing occurs, the entire cyst calcifies densely, and a lesion with this appearance is usually dead or inactive. Daughter cysts generally occur in a peripheral location and are typically slightly hypodense compared with the mother cyst. Unless the cysts are small or the patient is not a suitable candidate for surgical resection, the treatment of hydatid disease is surgically based because of the high risk of secondary infection and rupture. Medical treatment with albendazole relies on drug diffusion through the cyst membrane. The concentration of drug achieved in the cyst is uncertain but is better than that of mebendazole, and albendazole can be used as initial treatment for small, asymptomatic cysts.

Ascaris infection is particularly common in the Far East, India, and South Africa. Ova of the roundworm Ascaris lumbricoides arrive in the liver by retrograde flow in the bile ducts. The adult worm is 10 to 20 cm long and may lodge in the common bile duct, producing partial bile duct obstruction and secondary cholangitic abscesses. The ascaris may be a nucleus for the development of intrahepatic gallstones. The clinical presentation in an affected patient may include any of the following: biliary colic, acute cholecystitis, acute pancreatitis, or hepatic abscess. Plain abdominal radiographs, abdominal ultrasound, and endoscopic retrograde cholangiography (ERCP) all can demonstrate the ascaris as linear filling defects in the bile ducts. Occasionally worms can be seen moving into and out of the biliary tree from the duodenum. Treatment consists of administration of piperazine citrate, mebendazole, or albendazole in combination with ERCP extraction of the worms. (See Schwartz 9th ed., pp 1115-16.)

16. The best treatment for a symptomatic 6-cm simple hepatic cyst of the left lobe is

A. Aspiration alone

B. Aspiration and sclerotherapy

C. Laparoscopic fenestration

D. Left lobectomy

Answer: B

The preferred treatment for symptomatic cysts is ultra-sound- or CT-guided percutaneous cyst aspiration followed by sclerotherapy. This approach is approximately 90% effective in controlling symptoms and ablating the cyst cavity. If percutaneous treatment is unavailable or ineffective, treatment may include either laparoscopic or open surgical cysts fenestration. The laparoscopic approach is being used more frequently and is 90% effective. The excised cyst wall is sent for pathologic analysis to rule out carcinoma, and the remaining cyst wall must be carefully inspected for evidence of neoplastic change. If such change is present, complete resection is required, either by enucleation or formal hepatic resection. (See Schwartz 9th ed., pp 1118-19.)

17. An isolated mass in the liver which has a central scar on CT scan is most likely

A. An adenoma

B. Focal nodular hyperplasia

C. A hemangioma

D. Hepatocellular carcinoma

Answer: B

A good-quality biphasic CT scan usually is diagnostic of FNH, on which such lesions appear well circumscribed with a typical central scar (see Fig. 31-7). They show intense homogeneous enhancement on arterial phase contrast images and are often isodense or invisible compared with background liver on the venous phase. On MRI scans, FNH lesions are hypointense on T1-weighted images and isointense to hyperintense on T2-weighted images. After gadolinium administration, lesions are hyperintense but become isointense on delayed images. The fibrous septa extending from the central scar are also more readily seen with MRI. If CT or MRI scans do not show the classic appearance, radionuclide sulfur colloid imaging may be used to diagnose FNH based on select uptake by Kupffer cells.

The majority of hemangiomas can be diagnosed by liver imaging studies. On biphasic contrast CT scan, large hemangiomas show asymmetrical nodular peripheral enhancement that is isodense with large vessels and exhibit progressive centripetal enhancement fill-in over time (Fig. 31-7). On MRI, hemangiomas are hypointense on T1-weighted images and hyperintense on T2-weighted images. With gadolinium enhancement, hemangiomas show a pattern of peripheral nodular enhancement similar to that seen on contrast CT scans.

On CT scan, adenomas usually have sharply defined borders and can be confused with metastatic tumors. With venous phase contrast, they can look hypodense or isodense in comparison with background liver, whereas on arterial phase contrast subtle hypervascular enhancement often is seen (see Fig. 31-7). On MRI scans, adenomas are hyperintense on T1-weighted images and enhance early after gadolinium injection. On nuclear medicine imaging, they typically appear as ‘cold,’ in contrast with FNH.

HCCs are typically hypervascular with blood supplied predominantly from the hepatic artery. Thus, the lesion often appears hypervascular during the arterial phase of CT studies (Fig. 31-8) and relatively hypodense during the delayed phases due to early washout of the contrast medium by the arterial blood. MRI imaging also is effective in characterizing HCC. HCC is variable on T1-weighted images and usually hyperintense on T2-weighted images. As with contrast CT, HCC enhances in the arterial phase after gadolinium injection because of its hypervascularity and becomes hypointense in the delayed phases due to contrast washout. HCC has a tendency to invade the portal vein, and the presence of an enhancing portal vein thrombus is highly suggestive of HCC. (See Schwartz 9th ed., p 1120.)

Image

FIG. 31-7. Computed tomographic scans showing classic appearance of benign liver lesions. Focal nodular hyperplasia (FNH) is hypervascular on arterial phase, is isodense to liver on venous phase, and has a central scar (upper panels). Adenoma is hypovascular (lower left panel). Hemangioma shows asymmetrical peripheral enhancement (lower right panel).

Image

FIG. 31-8. Computed tomographic (CT) images of hepatocellular carcinoma (HCC) and peripheral cholangiocarcinoma. CT scans reveal a large (upper panel) and small (middle panel) hypervascular HCC. A hypovascular left lobe peripheral cholangiocarcinoma (Cholangio CA) is also shown (lower panel).

18. Standard therapy for a 4-cm right lobe hepatic adenoma is

A. Observation only

B. Arterial embolism to prevent further growth

C. Laparoscopic ablation

D. Surgical resection

Answer: D

Hepatic adenomas carry a significant risk of spontaneous rupture with intraperitoneal bleeding. The clinical presentation may be abdominal pain, and in 10 to 25% of cases hepatic adenomas present with spontaneous intraperitoneal hemorrhage. Hepatic adenomas also have a risk of malignant transformation to a well-differentiated HCC. Therefore, it usually is recommended that a hepatic adenoma (once diagnosed) be surgically resected. Oral contraceptive or estrogen use should be stopped when either FNH or adenoma is diagnosed. (See Schwartz 9th ed., p 1120.)

19. The best treatment for a 42-year-old patient with Child’s B cirrhosis and a single 4-cm hepatocellular carcinoma in segment VI is

A. Radiofrequency

B. Segmental resection with 1-cm margins

C. Right lobectomy

D. Liver transplantation

Answer: D

For patients without cirrhosis who develop HCC, resection is the treatment of choice. For those patients with Child’s class A cirrhosis with preserved liver function and no portal hypertension, resection also is considered. If resection is not possible because of poor liver function and the HCC meets the Milan criteria (one nodule 5 cm, or two or three nodules all 3 cm, no gross vascular invasion or extrahepatic spread), liver transplantation is the treatment of choice. (See Schwartz 9th ed., p 1121, and Fig. 31-9.)

Image

FIG. 31-9. Algorithm for the management of hepatocellular carcinoma (HCC). The treatment algorithm for HCC begins with determining whether the patient is a resection candidate or liver transplant candidate. Bili = bilirubin level (in milligrams per deciliter); Child’s = Child-Turcotte-Pugh class; lap = laparoscopic; LDLT = living-donor liver transplantation; LN = lymph node; MELD = Model for End-Stage Liver Disease; OLTx = orthotopic liver transplantation; Perc = percutaneous; RFA = radiofrequency ablation; TACE = transarterial chemoembolization; Tx = transplantation; UNOS = United Network for Organ Sharing; vasc. = vascular.