Appendicitis, the most common major surgical disease, is an inflammation of the vermiform appendix, a small, fingerlike projection attached to the cecum just below the ileocecal valve. This disorder occurs at any age, affecting both sexes equally; however, between puberty and age 25, it’s more prevalent in men. Since the advent of antibiotics, the incidence and mortality of appendicitis have declined. If untreated, this disease is fatal.

Appendicitis occurs when the appendix becomes inflamed from ulceration of the mucosa or obstruction of the lumen. It may result from an obstruction of the appendiceal lumen, caused by a fecal mass, stricture, barium ingestion, or viral infection. This obstruction sets off an inflammatory process that can lead to infection, thrombosis, necrosis, and perforation.

Cholelithiasis—the leading biliary tract disease—is the formation of stones or calculi (also called gallstones) in the gallbladder. The prognosis is usually good with treatment; however, if infection occurs, the prognosis depends on the infection’s severity and its response to antibiotics. Generally, gallbladder and duct diseases occur during middle age. Between ages 20 and 50, they’re six times more common in women, but the incidence in men and women equalizes after age 50, increasing with each succeeding decade.

Gallstone formation can give rise to a number of related disorders, including cholecystitis, choledocholithiasis, cholangitis, and gallstone ileus. The type of disorder that develops depends on where in the gallbladder or biliary tract the calculi collect. Although the exact cause of gallstone formation is unknown, abnormal metabolism of cholesterol and bile salts clearly plays an important role.

With cholecystitis, the gallbladder becomes acutely or chronically inflamed, usually because a gallstone becomes lodged in the cystic duct, causing painful gallbladder distention. In choledocholithiasis, gallstones pass out of the gallbladder and lodge in the common bile duct, causing partial or complete biliary obstruction. With cholangitis, the bile duct becomes infected; this disorder is commonly associated with choledocholithiasis and may follow percutaneous transhepatic cholangiography. In gallstone ileus, a gallstone obstructs the small bowel. Typically, the gallstone travels through a fistula between the gallbladder and small bowel and lodges at the ileocecal valve.

Cirrhosis is a chronic hepatic disease characterized by diffuse destruction and fibrotic regeneration of hepatic cells. As necrotic tissue yields to fibrosis, this disease alters liver structure and normal vasculature, impairs blood and lymph flow, and ultimately causes hepatic insufficiency. Obstruction to venous flow leads to portal hypertension, ascites, esophageal varices, and gastric varices. As the liver becomes cirrhotic, it can no longer change ammonia (waste product of protein metabolism) to urea so that it can be eliminated by the kidney. Elevated ammonia levels in the blood are thought to contribute to hepatic encephalopathy.

Most cases are a result of alcoholism, but toxins, biliary destruction, hepatitis, and a number of metabolic conditions may stimulate the destruction process. There are many types of cirrhosis; causes differ with each type and include:

Laënnec’s cirrhosis—also called portal, nutritional, or alcoholic cirrhosis—is the most common type.

Cirrhosis is characterized by irreversible chronic injury of the liver, extensive fibrosis, and nodular tissue growth. These changes result from: