Chapter 28 Liver
Principles of Surgery Companion Handbook
|Cysts and Benign Tumors|
|Encephalopathy and Coma|
|Surgery of Portal Hypertension|
|Fulminant Hepatic Failure|
The liver constitutes approximately one-fiftieth of total body weight. True division into right and left lobes (hemilivers) is in line with the fossa for the inferior vena cava posteriorly and the gallbladder fossa anteroinferiorly (Cantlie's line). Couinaud proposed a functional division of the liver related to the hepatic venous drainage (Fig. 28-1).
FIGURE 28-1 The functional division of the liver and the segments according to Couinaud's nomenclature. (From: Bismuth H: Surgical anatomy and anatomical surgery of the liver. World J Surg 6:2, 1982, with permission.)
Biliary Drainage Each sector is drained by a major segmental duct. The anterior and posterior sectoral ducts in the right lobe join to form the right hepatic duct, whereas the medial and lateral segmental ducts in the left lobe terminate in the left hepatic duct, which joins the right duct to form a common hepatic duct in the porta hepatis.
Blood Supply The afferent blood supply to the liver arises from two sources: (1) the hepatic artery, which carries oxygenated blood and accounts for approximately 25 percent of hepatic blood flow, and (2) the portal vein, which accounts for approximately 75 percent of hepatic blood flow and drains the splanchnic circulation. The common hepatic artery originates from the celiac axis, and it bifurcates into a right and left branch to the left of the line dividing the right and left lobes. The major right hepatic artery originates from the superior mesenteric artery in 17 percent of people. Intrahepatic anastomoses between the right and left hepatic arteries do not occur. The cystic artery usually is an extrahepatic branch of the right hepatic artery.
The portal venous system returns to the liver the blood that the celiac, superior mesenteric, and inferior mesenteric arteries supply to the gastrointestinal (GI) tract, pancreas, and spleen. The vessel is formed behind the pancreas by the confluence of the superior mesenteric and splenic veins and, at times, the inferior mesenteric vein. The portal vein resides posteriorly in relation to the hepatic artery and bile duct in the hepatoduodenal ligament. In the porta hepatis, the vein divides into two branches, which course to each lobe. The hepatic venous system begins in the liver lobules as a central vein into which the sinusoids empty, forming collecting veins that gradually increase in size and coalesce to form the three major hepatic veins. Total hepatic blood flow is 1500 mL/min/1.73 m2 of body surface.
The liver consists of four interrelated physiologic-anatomic units: the circulatory system, the biliary passages, the reticuloendothelial system, and functioning liver cells (hepatocytes).
The so-called liver function tests (Table 28-1) evaluate liver activity by assessing the degree of functional impairment.
TABLE 28-1 NORMAL VALUES FOR HEPATIC FUNCTION TESTS
Proteins Hepatic cells are responsible for the synthesis of albumin, fibrinogen, prothrombin, and other factors involved in blood clotting. Because the half-life of albumin is 21 days, impairment of hepatic synthesis must be present for over 3 weeks before abnormalities are noted.
Carbohydrates and Lipids Glycogenesis, glycogen storage, glycogenolysis, and the conversion of galactose into glucose all represent hepatic functions. Hypoglycemia is a rare accompaniment of extensive hepatic disease. The more common effect of hepatic disease is a deficiency of glycogenesis with resulting hyperglycemia. The liver is the major organ involved in the synthesis, esterification, and excretion of cholesterol. In the presence of parenchymal damage, both the total cholesterol and percentage of esterified fraction decrease.
Enzymes The three enzymes that achieve abnormal serum levels in hepatic disease and have been studied widely are alkaline phosphatase, serum glutamic oxalacetic transaminase (SGOT), and serum glutamic pyruvic transaminase (SGPT). SGOT is present in the liver, myocardium, skeletal muscles, kidney, and pancreas. Cellular damage in any of the above-mentioned tissues results in elevation of the serum level, and in the liver, most marked increases accompany acute cellular damage regardless of cause. Extremely high levels are noted in patients with hepatitis. SGPT is a more specific marker of liver disease. Elevations accompany acute hepatocellular damage. Serum alkaline phosphatase provides an indication of the patency of the bile channels. Elevation occurs in any form of obstruction including calculi, neoplasm, or intrahepatic cholestasis. In the presence of space-occupying lesions such as metastases, primary hepatic carcinoma, and abscesses, the alkaline phosphatase level also is increased. Nucleotidase levels are elevated in hepatobiliary disease.
Dye Excretion The hepatic removal of dyes from the circulation depends on hepatic blood flow, hepatocellular function, and biliary excretion. The presence of jaundice, fever, shock, hemorrhage, or cellular damage causes a disproportionate indocyanine green or sulfobromophthalein (Bromsulphalein) retention.
Coagulation Factors In liver disease, multiple coagulation defects may occur. Two mechanisms contribute to the deficiency of coagulation factors: (1) in obstructive jaundice, the bile source required for the absorption of the fat-soluble vitamin K results in a decreased synthesis of prothrombin, and (2) hepatocellular dysfunction is accompanied by an inability of the liver to synthesize prothrombin. Decreases in factors V, VII, and IX and fibrinogen also have been noted in hepatic disease. Cirrhosis may have increased fibrinolysis.
Needle Biopsy Almost 100 percent accuracy has been demonstrated for both posthepatitic and postnecrotic cirrhosis. Intrahepatic cholestasis, hepatitis, and cellular degeneration resulting from toxicity are readily diagnosed. Focal lesions occassionally may be missed. Needle biopsy is contraindicated for suspected hemangioma.
Ultrasound, Computed Tomography, Magnetic Resonance Imaging, and Scintigrams Preoperative ultrasound (US) has its highest yield in defining hepatic abscesses, cystic lesions, and most hemangiomas. US and duplex scanning can determine the patency of a portasystemic shunt noninvasively. Computed tomography (CT) is used with or without vascular enhancement. For most lesions, CT provides the best results. Magnetic resonance imaging (MRI) is particularly applicable for assessing vascular lesions.
Angiography Angiography may depict hepatic tumors, both primary and metastatic. When used in conjunction with CT, sensitivity and specificity are increased. Angiography also demonstrates extrahepatic vascular anatomy and provides a road map for the surgeon.
See Chap. 6, Trauma.
Hepatic abscesses are related to two distinct groups of pathogens: pyogenic bacteria and Entamoeba histolytica.
Incidence The highest percentage occur in the sixth and seventh decades.
Etiology Causes include (1) ascending biliary infection, (2) hematogenous spread via the portal venous system, (3) generalized septicemia with involvement of the liver by way of the hepatic arterial circulation, (4) direct extension from intraperitoneal infection, or (5) other causes, including hepatic trauma. The most frequent antecedent cause has been cholangitis secondary to calculi or carcinoma in the extrahepatic biliary duct system. The second most common cause is related to generalized septicemia. There is an increased incidence in immunocompromised patients. Cultures are positive in over 90 percent; Escherichia coli, Klebsiella, and Streptococcus are most commonly isolated. Staphylococcus and Pseudomonas are occurring more frequently, and mixed bacterial and fungal abscesses are noted in about 25 percent. Abscesses may be solitary, multiple, and multilocular.
Clinical Manifestations The primary clinical manifestation is fever, frequently accompanied by chills, profuse sweating, nausea, vomiting, and anorexia. Pain is a late symptom and is more common with large, solitary abscesses. Hepatic tenderness is present in 50 percent.
Diagnostic Studies Leukocytosis is usual; anemia is frequent. Positive blood cultures are seen in 40 percent of patients. Liver function tests are not diagnostic, but elevation of the alkaline phosphatase level is the most frequent abnormality. CT scan is the most accurate radiographic study (over 90 percent), followed by US (80 percent) and radionuclide scans (70 percent).
Treatment Treatment is based on appropriate antibiotic therapy combined with drainage in selected patients. Intravenous antibiotics are usually administered for 2 weeks, followed by 1 month of oral therapy. Abscesses may be drained percutaneously under US or CT control. Equivalent results have been reported for percutaneous and surgical drainage. Surgical access may be transthoracic or transabdominal. Occasionally, for multiple abscesses confined to a lobe, treatment is best managed by resection.
Prognosis and Complications For percutaneous and surgical drainage, there is 7.520 percent mortality (for multiple abscesses, the rate is significantly increased).
Ten percent of the population is infected with Entamoeba histolytica. Amebic abscesses usually are diagnosed in middle-aged adults with male-female ratio of 9:1. Organisms reach the liver via the portal system. The abscess is usually a solitary right lobe abscess with anchovy paste fluid.
Clinical Manifestations Clinical manifestations include fever, liver pain (88 percent), and occasionally right shoulder pain. Fever with diaphoresis and rigors is seen in 75 percent. Fifty percent of patients show antecedent diarrhea; bloody, mucous stools are seen in children. The liver is tender and enlarged on examination. Jaundice is rare.
Diagnostic Studies/Complications Leukocytosis and anemia accompany prolonged disease. The recovery rate of ameba in stool is 15.4 percent. Liver function tests are not helpful. The indirect hemagglutination test usually is positive. Scans also are useful. Aspiration of the cavity shows characteristic material, trophozoites in less than one-third. Secondary bacterial infection is evident in 22 percent. Abscesses may rupture (69 percent) or extend into adjacent organs.
Treatment Amebicidal drugs are used first; metronidazole is the drug of choice. Treatment may require aspiration and drainage if symptoms persist, the abscess remains apparent radiographically, or it is secondarily infected.
Prognosis The mortality rate is less than 5 percent in uncomplicated cases; with complications, the rate can rise to 43 percent.
These include degenerative, dermoid, lymphatic, retention, and proliferative cysts. Solitary cysts usually occur in the right lobe and have clear contents. The liver may be honeycombed, polycystic, which is associated with polycystic kidneys. Rarely, a polycystic liver may cause portal hypertension. Traumatic cysts usually are single and filled with bile. Cystadenomas are filled with mucoid material. Cysts usually grow slowly with few symptoms and present as painless right upper quadrant masses. Symptoms result from pressure on adjacent organs. Pain occurs with rupture, torsion, or hemorrhage. Jaundice is rare. Liver function tests have little value. CT and US are very useful for diagnosis.
Treatment Asymptomatic cysts require observation only. Surgical treatment can consist of complete extirpation. Large, deep, sterile cysts may be widely unroofed. Purulent contents demand external drainage. Polycystic livers may require nonanatomic resection and wide fenestration. Prognosis follows that of the associated renal polycystic disease, if any.
Hydatid cysts usually are unilocular and caused by Echinococcus granulosus. The alveolar type is caused by E. multiocularis. Seventy percent are located in the liver; one-third are multiple. The right lobe is affected in 85 percent. The cyst is two-layered and encapsulated with the contents under pressure and is colorless, opalescent. Daughter cysts can be inside the main cyst. Alveolar disease has no capsule with multiple metastases, blood, and lymphatic invasion.
Complications Complications include intrabiliary rupture (510 percent), suppuration with biliary bacteria, and intraperitoneal or intrapleural rupture.
Clinical Manifestations These cysts usually are asymptomatic. Early symptoms result from pressure on adjacent organs. Pain, tenderness, and palpable mass are common. If the cyst is secondarily infected, symptoms are those of pyogenic abscess. Hydatid cyst may present with anaphylaxis if there is an intraperitoneal rupture. Biliary rupture can present with colic, jaundice, and urticaria.
Diagnostic Studies Round, calcified shadows are seen on plain films. CT scan is very useful. Indirect agglutination is positive in 85 percent. Casoni's skin test is positive in 90 percent.
Treatment Treatment is surgical. Cysts must be removed without contaminating the peritoneal cavity. Cysts may be drained intraoperatively and flushed with hypertonic saline, alcohol, or hibitane before excision. Large cysts may require partial hepatectomy. The cavity may be managed by omentoplasty and simple closure. External drainage has a high complication rate. In the past, alveolar disease of the liver was inevitably fatal, but more recently, satisfactory results have been obtained with extensive hepatic resection.
Hamartoma This lesion is composed of normal tissues arranged in disorderly fashion. Hamartomas are firm, nodular, encapsulated, and cystic and usually are of no clinical significance.
Adenoma This tumor may be related to oral contraceptives, pregnancy, diabetes mellitus, or glycogen storage disease. It should be resected particularly if it is enlarging or bleeding. Because of the risk of bleeding and malignant potential, adenomas should be removed.
Focal Nodular Hyperplasia (FNH) Focal nodular hyperplasia is a solitary, tan, unencapsulated tumor near the liver edge that usually is asymptomatic; it rarely ruptures. It should be resected only if symptomatic. Deep biopsy is necessary for diagnosis.
Hemangioma This is the most common liver nodule. The female-male ratio is 5:1. There is no malignant potential. Most hemangiomas are asymptomatic; bruit is rare. Symptoms are related to size. They rarely rupture and hemorrhage. Diagnosis is by angiography, CT, US, MRI, or scintigram. Avoid needle biopsy because of bleeding. Infants may have high-output congestive heart failure and may respond to steroids or hepatic artery ligation. Adults should only be resected for symptoms and when size is greater than 45 cm.
Incidence Primary liver carcinoma is common in Asians and African aborigines. In children, hepatoblastoma is common before age 2. Aflatoxins and low-protein diets have been implicated etiologically. Postnecrotic cirrhosis frequently precedes, with serologic markers for hepatitis B virus or hepatitis C antibody in patients living in endemic areas.
Pathology Hepatocellular carcinoma (most common), followed by cholangiocarcinoma (bile duct cancer) and hepatoblastoma, an immature variant in children. Fibrolamellar carcinoma is a hepatocellular variant occurring in young adults.
There is frequent invasion of the portal and hepatic veins. Extension is via (1) centrifugal growth, (2) parasinusoidal extension, (3) venous spread, and (4) distal metastasis by lymphatic and vascular systems, most often to nodes and lungs. Metastases occurs in 4873 percent.
Clinical Manifestations Weight loss and fatigue are evident in 80 percent, pain in 50 percent. Hepatomegaly is very common; splenomegaly and portal hypertension are likely in 33 percent. Jaundice and ascites are common. Children usually present with a mass.
Diagnostic Evaluation Alkaline phosphatase and 5'-nucleotidase levels usually are elevated. The bilirubin level often is normal. Alpha-fetoprotein (AFP) is present in 3075 percent. Arteriography and CT/MRI are useful. Preoperative needle biopsy also is useful. Intraoperative US is used to define resection limits.
Treatment The only chance for survival is surgical excision. Cirrhosis compromises resection possibilities. Use of intraoperative US has permitted limited resections, particularly in cirrhotic patients. Transarterial chemoembolization has achieved 1-, 2-, and 5-year survival rates of 51, 24, and 6 percent, respectively, while decreasing the tumor size in almost 33 percent of patients. Unresectable hepatocellular carcinomas may be converted to resectable lesions with combined radiation and chemotherapy.
Percutaneous ethanol injection has resulted in the disappearance of tumors less than 4.5 cm in diameter. Cryosurgery using an intraoperatively placed probe that delivers liquid nitrogen also has effected tumor necrosis and destruction. Transplantation and resection yield equivalent 5-year survival rates of approximately 50 percent, but the recurrence rate is lower in patients who were transplanted. Transplantation achieves the best results in patients with small, uninodular or binodular lesions. Resection of extrahepatic recurrences of hepatocellular carcinomas has resulted in several 5-year survivals.
In the case of hepatoblastoma, particularly in children, lesions often deemed not resectable can be converted into resectable tumors that have potential for cure. A combination of preoperative chemotherapy followed by resection has resulted in a cure rate of 90 percent in children.
Prognosis Prognosis is extremely poor for adults but better for fibrolamellar carcinoma. Resectable children under age 2 have better survivals.
OTHER PRIMARY NEOPLASMS
These include angiosarcomas (vinyl chloride, Thorotrast), mesenchymomas, and infantile hemangioendotheliomas.
Metastatic neoplasms are the most common malignant liver tumor with a ratio 20:1 to primary tumors. Metastases in the liver are noted in 2550 percent of all cancer deaths. Routes to the liver are via (1) portal vein, (2) lymphatics, (3) hepatic artery, and (4) direct extension. Metastases often grow more rapidly than the original lesion.
Clinical Manifestations Symptoms are evident in 67 percent, with pain, ascites, jaundice, anorexia, and weight loss. A mass is seen in 50 percent. Flushing is evident in hepatic carcinoid.
Diagnosis The alkaline phosphatase level is elevated in over 80 percent, SGOT elevation is seen in 67 percent, and the AFT level is normal. Carcinoembryonic antigen (CEA) may be elevated in colon metastases. CT/MRI, particularly CT with intraarterial infusion, angiography, and intraoperative US are all useful.
Treatment Resection should be considered if (1) the primary is controlled, (2) there are no other metastases, (3) the patient will tolerate the procedure, and (4) total extirpation is possible. Resection of metastases has a survival benefit for colorectal carcinoma and Wilms' tumor. Twenty percent of colon carcinomas have metastases, of which 25 percent are resectable; 50 percent have other negating factors. A multi-institutional study of liver resection for colorectal metastases reported a 33 percent 5-year survival and a 21 percent 5-year disease-free survival. Colorectal hepatic metastases, initially considered unresectable, have been treated with doxorubicin. This resulted in regression to a size that permited resection.
Intraarterial infusion chemotherapy may provide symptomatic relief, but most series show no improvement over intravenous therapy. Cures of metastatic Wilms' tumor by liver resection combined with chemotherapy and radiation have been reported.
Indications include (1) trauma with devascularization of hepatic tissue, (2) cysts, (3) granulomas, (4) primary neoplasms, and (5) secondary neoplasms. Up to 80 percent resection may be tolerated in noncirrhotics. Regeneration occurs from marked hypertrophy of remaining tissue. Insulin is an anabolic factor.
Management of the Patient Preoperative therapy is directed at maintaining optimal liver function and correcting any defects that may be present. A diet high in calories, proteins, and carbohydrates is used, and the administration of albumin may be required to achieve normal levels. Vitamin K is given routinely until a normal prothrombin time results. In the presence of jaundice, other fat-soluble vitamins are added. Fresh frozen plasma will rapidly replenish coagulation factors. Because many patients have a reduced hematocrit, transfusion with fresh whole blood rich in platelets and coagulation factors is indicated. Major hepatic resection is attended by a prohibitive mortality rate in the patient with sulfobromophthalein retention greater than 35 percent, a serum albumin level lower than 2.0 g, and an increased prothrombin time that does not respond to parenteral vitamin K. Postoperatively, infusion of 10% glucose is continued until the patient maintains an adequate oral intake to obviate severe hypoglycemia, which has been reported. After more intensive resections, daily administration of 2550 g albumin usually is required for 710 days to maintain the serum level above 3 g/dL. Antibiotics are administered prophylactically. Analgesics and hypnotics that are detoxified by the liver are used only sparingly. Intraabdominal abscess formation and sepsis are the most common complications of major hepatic resection, occurring in 2030 percent of patients. Subphrenic abscesses usually can be managed with percutaneous drainage.
Operative Procedures The major aim is to prevent/control hemorrhage. The porta hepatis may be clamped safely for 60 min. Resection follows anatomic planes of segmental anatomy based on portal distribution. The liver is mobilized by dividing the triangular ligament, coronary ligament, and ligamentum teres. Porta hepatis dissection defines the artery, vein, and duct to be removed, which are temporarily occluded. Glisson's capsule is incised, and the hepatic parenchyma is cleaved bluntly, ligating ducts and vessels and heading toward the hepatic veins, which are then doubly ligated at the cava. This is followed by division of porta hepatis structures.
On the basis of new concepts of segmental anatomy, the following classification of hepatic resection is applicable (Fig. 28-2): (1) Subsegmental or wedge resection is removal of an area of the liver that is less than a segment and without an anatomic dissection plane. (2) Left lateral segmentectomy (formerly left lobectomy) is excision of the liver mass to the left of the left segmental fissure along an anatomic plane. (3) Left medial segmentectomy is resection between the main interlobar fissure and the left segmental fissure. (4) Left lobectomy (left hepatectomy) is excision of all hepatic tissue to the left of the main lobar fissure. (5) Right lobectomy (right hepatectomy) is removal of the liver to the right of the main lobar fissure. (6) Extended right lobectomy is excision of the entire lobe plus the medial segment of the left lobe (trisegmentectomy), i.e., excision of all tissue to the right of the umbilical fossa, fossa for the ligamentum venosum, and the ligamentum teres. Based on portal distribution, there are eight hepatic segments that can be resected individually or as combinations (see Fig. 28-1).
FIGURE 28-2 Nomenclature for hepatic resection.
Etiology (Table 28-2) The causes include (1) increased inflow (rare), (2) extrahepatic outflow obstruction, (3) extrahepatic portal obstruction, and (4) intrahepatic obstruction. The overwhelming majority (>90 percent) of cases result from intrahepatic obstruction. Contributing factors include (1) fibrosis with portal venule compression, (2) compression by regenerative nodules, (3) increased arterial flow, (4) fatty infiltration and inflammation, and (5) intrahepatic vascular obstruction. Nutritional cirrhosis is the most common cause worldwide, which is related to ethanol consumption in Western civilization. Resistance to flow is postsinusoidal (on the hepatic venous side of the sinusoid). Postnecrotic cirrhosis accounts for up to 12 percent but represents the major cause in the Orient.
TABLE 28-2 ETIOLOGY OF PORTAL HYPERTENSION
Pathophysiology Elevated pressure in the portal venous system leads to collateral venous flow. The normal portal pressure is less than 25 cmH2O; mean is 21.5 cmH2O. Pressure may be measured intraoperatively, by direct splenic puncture, or by occlusive hepatic venous pressure (OHVP), which is analogous to the pulmonary wedge pressure. Anatomy may be defined by splenoportography or the venous phase of mesenteric arteriography. Normally, no collaterals should be seen. Collaterals that become functional are (1) hepatopetal collaterals, which shunt blood from an obstructed extrahepatic portal system to the normal intrahepatic vasculature (they are the veins of Sappey and the cystic, epiploic, hepatocolic, hepatorenal, diaphragmatic, and suspensory ligament veins), and (2) hepatofugal collaterals, which are the most common type (they are the coronary and esophageal veins, the superior hemorrhoidal veins, the umbilical vein, and the veins of Retzius). These vessels shunt blood away from the liver to the systemic venous system.
Initially, submucosal veins enlarge; later, submucosa disappears, and veins that line the inside of the esophagus erode from esophagitis and hemorrhage. Gastric varices predominate in the cardia. Thirty percent of cirrhotics with varices will bleed within 2 years of diagnosis. Seventy percent of these patients die within 1 year of the first hemorrhage; 60 percent rebleed within 1 year.
Acute Bleeding Usually this is the first sign of portal hypertension in children. In adults, varices account for 2533 percent of massive upper GI bleeds. In cirrhotic patients, bleeding is a result of varices in 50 percent, gastritis in 30 percent, and ulcers in 9 percent. A specific diagnosis must be made before treatment. Physical examination shows stigmata for cirrhosis. Esophagoscopy is the most accurate tool. Arteriography may be useful in ulcer disease.
Treatment Nonoperative Techniques Balloon tamponade is risky and has a failure rate of 2555 percent. Endoscopic variceal sclerosis or vein ligation may control bleeding in up to 93 percent of patients with similar mortality to emergency shunts. Ligation is equivalent to that of sclerotherapy, with fewer complications. Vasopressin or somatostatin reduces portal flow by 40 percent. Peripheral venous infusion is the route of choice. Vasopressin is risky in patients with coronary disease. Inderal may be used as prophylaxis. Transjugular intrahepatic portosystemic shunts (TIPS) can effectively lower portal pressure.
The incidence of TIPS shunt dysfunction is 1560 percent over a 6- to 12-month period. Patency can be reestablished. TIPS are particularly applicable in patients with minimal hepatic reserve in whom a transplant is indicated.
Surgical Therapy This includes transesophageal ligation and emergency portosystemic shunt. The results of transesophageal ligation have improved significantly with stapling techniques, and results better than those with sclerotherapy have been reported. A more liberal use of emergency portacaval shunts to stop bleeding has been advised for the cirrhotic patients whose bleeding cannot be controlled by nonoperative measures. Emergency portosystemic shunt is an important option for selected patients with acute variceal bleeding. Emergency shunt performed on 400 unselected patients within 8 h of initial contact indicated survival rates of 85, 78, and 71 percent at 30 days, 5 years, and 10 years, respectively. In most series, the mortality rate for patients with Child's class C disease remains high. Pediatric variceal bleeding often stops spontaneously with bed rest and sedation. Important tenets in treatment include correction of coagulation deficits with component therapy. Acute bleeding in cirrhotics exacerbates or will induce encephalopathy.
Prevention of Recurrent Hemorrhage Shunting procedures in adults whose bleeding has stopped are much safer if performed electively. Prognosis is correlated with hepatic function as per Child's criteria. Patients with nutritional, alcoholic, or cryptogenic cirrhosis have a worse prognosis than do patients with biliary cirrhosis or extrahepatic portal vein obstruction. For patients with end-stage liver disease and marked hepatocellular dysfunction, after the bleeding has been controlled with sclerotherapy or TIPS, orthotopic liver transplantation often is appropriate.
Mechanisms are poorly understood. Portal hypertension is a contributory but not sole etiologic factor. Hypoalbuminemia and reduced serum osmotic pressure contribute to ascites. Impairment of hepatic venous outflow appears to be most important. Accompanying ascites is the retention of sodium and water.
Treatment Treatment includes rest, nutritional supplementation, low sodium intake, and potassium repletion. Diuretics include furosemide, chlorothiazide (first line), and aldosterone antagonists (spironolactone). Multiple paracenteses are contraindicated. Intractable ascites may require peritoneal venous shunts (complications include disseminated intravascular coagulation). TIPS also have been effective.
Splenomegaly accompanies portal hypertension. Subsequent hypersplenism may follow (white blood cell count < 4000/mm3, platelet count < 100,000/mm3). Splenectomy rarely is indicated and negates future selective shunting.
Portal-systemic encephalopathy rarely occurs in portal hypertension without coexisting hepatocellular dysfunction. Portacaval shunts may show up to 38 percent incidence. Physiologically, there is hyperammonemia secondary to portal-systemic collaterals and impairment of the ornithine-citrulline-arginine cycle. Dietary protein and intraluminal intestinal blood (variceal bleed) are major contributors. Endogenous intestinal urea production also contributes. Clinical manifestations include altered consciousness, reflexes, and motor activity, which can progress from confusion to frank coma.
Treatment Treatment should focus on reducing nitrogen within the gut, reducing ammonia production, and enhancing ammonia metabolism. This includes (1) restriction of protein intake, (2) control of bleeding, (3) GI catharsis (lactulose), (4) intestinal bacterial reduction (neomycin), and (5) intraluminal ammonia trapping (lactulose).
PROCEDURES THAT DIRECTLY ATTACK BLEEDING VARICES
These include transesophageal ligation of varices and esophageal transection. Control is only temporary, with 50 percent of cirrhotic survivors rebleeding. The Sugiura procedure includes esophageal transection, paraesophageal devascularization, splenectomy, and vagotomy with or without drainage. It has a high mortality and has a significant rebleed rate.
PROCEDURES THAT REDUCE PORTAL PRESSURE
These are classified as totally or partially diverting shunts. The most basic procedure is the end-to-side portacaval shunt, which completely diverts all portal inflow from the liver to the vena cava. The side-to-side portacaval shunt diverts portal flow but additionally allows reversed portal outflow from the liver. Other functional side-to-side shunts include the mesocaval, central splenorenal, and H-graft procedures. In decompressing the portal vein, all these do not preserve hepatic portal inflow. The distal splenorenal or Warren shunt is truly selective in decompressing varices while maintaining portal perfusion via a continued hepatic portal hypertension. This procedure is associated with less encephalopathy, but statistical differences in true survival, long-term preservation of portal flow, and ascites are unproved.
Shunt Selection Shunt selection should include preoperative portograms to assess portal vein patency. Budd-Chiari syndrome mandates a side-to-side shunt. Ascites may or may not alter shunt preference, with side-to-side shunts having the lowest incidence. If subsequent orthotopic transplantation is anticipated, it is preferable to consider a distal splenorenal shunt.
Patient Selection This includes evaluation of ascites, coagulation deficits, and liver function (bilirubin, sulfobromophthalein retention). Child's classification is predictive of operative morbidity and mortality. Overall, group A patients have nearly no elective mortality, whereas group C patients have up to 53 percent operative mortality.
Operative Technique Should always include pre- and postshunt portal pressure measurements.
Complications of Portal-Systemic Shunts Complications include intraoperative bleeding or shunt failure, postoperative rebleeding, hepatic failure, hepatorenal syndrome, cardiorespiratory failure, and delayed complications such as encephalopathy, hemosiderosis, and ulcer disease.
PORTACAVAL SHUNT FOR GLYCOGEN STORAGE DISEASE AND HYPERCHOLESTEROLEMIA
Improvement occurs after portacaval shunt in children with type I glycogen storage disease; there is no evidence of encephalopathy. The shunts also are used for type 2 hypercholesterolemia.
This is sudden, severe hepatic failure secondary to massive cellular necrosis. The usual origin is acute viral hepatitis. It is also seen with Reye syndrome and with chemical toxins (carbon tetrachloride). Therapy is supportive and includes hemo- and peritoneal dialysis, exchange transfusions, and plasmapheresis. Mortality is 8590 percent. Spontaneous recovery occurs in 1020 percent. Orthotopic liver transplantation is the treatment of choice in moribund patients.
For a more detailed discussion, see Schwartz SI: Liver, chap. 28 in Principles of Surgery, 7th ed.
Copyright © 1998 McGraw-Hill
Seymour I. Schwartz
Principles of Surgery Companion Handbook