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Intestinal Electrolyte Absorption and Secretion

The GI tract processes 8 to 9 L of fluid daily that is derived from oral intake and endogenous exocrine secretions. Intestinal fluid absorption functions with 98% efficiency, allowing only 100 to 200 mL to be excreted each day. The intestine also extracts nutrients, vitamins, and minerals from ingested materials; excludes destructive antigens and microbes; and excretes waste ( Fig. 101.1 ). This multitasking is achieved…

Colonic Motor and Sensory Function and Dysfunction

Each day, 1200 to 1500 mL of ileal effluent enter the colon, 200 to 400 mL of which are excreted as stool. The colon mixes its contents to facilitate transmural exchange of water, electrolytes, and short-chain fatty acids and, in doing so, stores stool for extended periods. The mixing process involves rhythmic to-and-fro motions, together with short stepwise movements of contents, resulting in an overall net…

Small Intestinal Motor and Sensory Function and Dysfunction

Efficient absorption of nutrients and maintenance of orderly aboral movement of chyme and indigestible residues are the most important goals of small intestinal motor and sensory function. Small intestinal motility is also critically important in preventing SIBO (see Chapter 105 ). This is achieved by the net aboral flow of luminal contents during both the fed and fasting states, probably with the assistance of the gatekeeper…

Anatomy, Histology, Embryology, and Developmental Anomalies of the Small and Large Intestine

Anatomy Macroscopic Features Small Intestine The small intestine is a specialized tubular structure within the abdominal cavity in continuity with the stomach proximally and the colon distally. The small bowel increases in length from about 250 cm in the term newborn to about 600 to 800 cm in the adult. The caliber of the small intestine gradually diminishes from proximal to distal, and there is a…

Liver Transplantation

Although specific treatments for certain chronic liver diseases may favorably alter their natural history by diminishing, halting, or permitting regression of hepatic fibrosis, once major complications of cirrhosis such as ascites or hepatic encephalopathy develop, treatment options are limited and typically do not extend or significantly improve quality of life. Interventions such as variceal band ligation and placement of a TIPS can effectively control life-threatening bleeding…

Hepatic Tumors and Cysts

Hepatic mass lesions include tumors, tumor-like lesions, abscesses, cysts, hematomas, and confluent granulomas. Hepatic tumors may originate in the liver—from hepatocytes, bile duct epithelium, or mesenchymal tissue—or spread to the liver from primary tumors in remote or adjacent organs. In adults in most parts of the world, hepatic metastases are more common than primary malignant tumors of the liver, whereas in children, primary malignant tumors outnumber…

Acute Liver Failure

ALF is characterized by a sudden insult to the liver with catastrophic consequences, usually in the absence of preexisting liver disease. Coagulopathy and encephalopathy are the twin cardinal features that reflect the severity of liver injury, and both are required to make the clinical diagnosis of ALF, although significant coagulopathy in the absence of definite encephalopathy has been described as “acute liver injury.” , A number…

Hepatic Encephalopathy, Hepatorenal Syndrome, Hepatopulmonary Syndrome, and Other Systemic Complications of Liver Disease

Chronic liver disease and ALF disrupt normal homeostasis and cause systemic manifestations that may dominate the clinical features of liver disease. Most of these extrahepatic syndromes are reversible with LT. Hepatic Encephalopathy The term hepatic encephalopathy (HE) encompasses a wide array of transient and subtle reversible neurologic and psychiatric manifestations usually found in patients with chronic liver disease and portal hypertension, but also seen in patients…

Ascites and Spontaneous Bacterial Peritonitis

Ascites is defined as the abnormal accumulation of fluid in the peritoneal cavity. In Western countries, cirrhosis is the most common cause of ascites, representing over 80% of cases. In the remaining cases, ascites may be caused by other conditions such as heart failure, malignancies, tuberculosis, or pancreatic disease ( Table 93.1 ). This chapter focuses on the pathophysiology, evaluation, and management of cirrhotic ascites and…

Portal Hypertension and Variceal Bleeding

Variceal hemorrhage, hepatic encephalopathy, and ascites—the major complications of cirrhosis of the liver (see Chapters 74, 93, and 94 )—result from portal hypertension, defined as an increase in hepatic sinusoidal pressure to 6 mm Hg or greater. Portosystemic collaterals decompress the hypertensive hepatic sinusoids and give rise to varices at the gastroesophageal junction and elsewhere. Normal Portal Circulation The portal venous system carries capillary blood from…

Primary Biliary Cholangitis

Acknowledgments The authors thank Jayant A. Talwalkar and the late Paul Angulo for their contributions to this chapter. PBC is an autoimmune liver disease that generally affects middle-aged women and is the most common chronic cholestatic liver disease in adults in the USA. PBC is characterized by progressive intrahepatic bile duct destruction, which leads to cholestasis, complications, and symptoms related to cholestasis, cirrhosis, and portal hypertension.…

Autoimmune Hepatitis

Autoimmune hepatitis (AIH) is a disease of unknown cause that is characterized by the presence of autoantibodies, hypergammaglobulinemia, and histologic features of interface hepatitis ( Fig. 90.1 ) and lymphoplasmacytic infiltration ( Fig. 90.2 ). Diagnosis requires the exclusion of other chronic liver diseases that have similar features, including Wilson disease, chronic viral hepatitis, drug-induced liver disease, NAFLD, and the immune cholangiopathies (PBC and PSC). Centrilobular…

Liver Disease Caused by Anesthetics, Chemicals, Toxins, and Herbal and Dietary Supplements

Contemporary inhalation and parenterally administered anesthetics are rarely hepatotoxic. Although halothane hepatitis is now largely of historical interest in Western nations, it remains in use elsewhere, with ongoing reports of acute liver injury. , In contrast to the largely unpredictable hepatotoxicity seen with more modern anesthetics and most other medicinal agents (see Chapter 88 ), liver damage caused by occupationally and environmentally encountered chemical compounds and…

Liver Disease Caused by Drugs

Hepatic Drug Metabolism Role of the Liver in Drug Elimination By virtue of the portal circulation, the liver is highly exposed to drugs and other toxins absorbed from the intestine. Most drugs tend to be lipophilic compounds that are readily taken up by the liver but cannot be easily excreted unchanged in bile or urine. The liver is well equipped to handle these agents by an…

Nonalcoholic Fatty Liver Disease

The global obesity epidemic has dramatically increased the prevalence of NAFLD and made it the leading cause of chronic liver disease in Western nations. NAFLD is considered the hepatic manifestation of the metabolic syndrome and shares a strong association with type 2 diabetes mellitus, obstructive sleep apnea (OSA), and cardiovascular disease. Although cardiovascular disease is the leading cause of death in patients with NAFLD, the subset…

Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) remains a challenging enigma for basic scientists and clinicians. Despite extensive research and clinical trials since the 1940s, many important facets of this disease have yet to be resolved. Paramount among these important questions are the following: (1) Why does cirrhosis develop in only a small fraction of heavy alcohol abusers? (2) What is the pathogenesis of severe ALD? (3) What are…

Vascular Diseases of the Liver

Vascular disorders of the liver are characterized by a primary alteration in blood or lymphatic vessels, excluding the vascular changes secondary to parenchymal or biliary diseases. Primary alterations consist of obstruction, fistula, aneurysm, or absence (due to agenesis or disappearance) affecting the large or small vessels (or both). This chapter reviews a heterogeneous group of disorders of the hepatic vasculature as well as liver involvement in…

Bacterial, Parasitic, and Fungal Infections of the Liver, Including Liver Abscesses

The liver serves as the initial site of filtration of absorbed intestinal luminal contents and is particularly susceptible to contact with microbial antigens of all varieties. In addition to infection by viruses (see Chapter 78, Chapter 79, Chapter 80, Chapter 81, Chapter 82, Chapter 83 ), the liver can be affected by (1) spread of bacterial or parasitic infection from outside the liver; (2) primary infection…

Hepatitis Caused by Other Viruses

In addition to hepatitis A to E, a number of other viruses have been shown to be hepatotropic in that viremia is occasionally associated with elevations in serum aminotransferase levels and viral replication may occur in hepatocytes; however, causality with significant acute or chronic liver disease has been difficult to establish. Such viruses include human pegivirus (HPgV) (formerly known as hepatitis G virus [HGV] and the…

Hepatitis E

Acknowledgment This chapter is dedicated to the memory of Krzysztof Krawczynski, MD, PhD, who contributed to the chapter in previous editions of the book. Hepatitis E is a form of viral hepatitis caused by HEV. The disease, often acute, self-limited, and associated with icterus, was first recognized in the 1980s, when sera collected during a large epidemic in Delhi, India, in 1955, and during another epidemic…