ACUTE PANCREATITIS



Definition. Acute pancreatitis is an acute, in­flammatory disorder of the pancreas associated with edema, swelling, and various amounts of au-todicestion, necrosis, and hemorrhage. It is usu­ally defined clinically by a symptom complex with an associated elevation of serum amylase. It is useful to consider acute pancreatitis as a single clinical entity, although it may be of diverse etiol­ogies, may vary greatly in severity, and may shade into chronic relapsing pancreatitis and chronic pancreatitis (to be considered subsequently).

Etiology and Pathogenesis. The disorders most commonly associated with acute pancrea­titis in the United States are listed in Table 42-2. Of these, alcoholism and biliary tract disease are the most important. The pathogenesis of acute pancreatitis is thought to be autodigestion due to inappropriate intrapancreatic activation of pro­teases (Fig. 42-4). Just why this occurs usually is unknown, although it is speculated that alcohol produces obstructive inspissated proteinaceous plugs in pancreatic ducts and that gallstones, passing through the sphincter of Oddi, cause ob­struction and possibly bile regurgitation into the pancreatic duct. Simply ligating the pancreatic duct does not usually cause acute pancreatitis, however, so that other unexplained factors are probably involved. Knowledge of the association of acute pancreatitis with the conditions listed in Table 42-2 is important for two reasons: (a) it suggests the possibility in a given patient, and (b) pre­venting recurrent pancreatitis often depends on reversal of these associated abnormalities.

Clinical Manifestations. The most important symptom of acute pancreatitis is abdominal pain,which is characteristically steady, severe, and epi­gastric in location with later radiation to the back and partially relieved by leaning forward. The pain is highly variable, however, and may be rel­atively mild or diffuse. The abdgmen is usually tender, without signs of peritoneal irritation, and nausea and vomiting are absent. Severe cases dis­tend the abdomen with ileus and produce high fever, confusion, tachycardia, and, sometimes, impending shock. Rarer features are (1) discol­oration in the flanks (Grey-Turner’s sign) or around the umbilicus (Cullen’s sign) in hemor­rhagic pancreatitis, (2) subcutaneous fat necrosis presenting as tender, red subcutaneous nodules, (3) ascites, (4) atelectasis and/or left-sided pleural effusion, (5) adult respiratory distress syndrome, (6) jaundice, and (7) an epigastric mass repre­senting a pseudocyst.

Diagnosis. The diagnosis of acute pancreatitis must be entertained in any patient with the acute onset of severe, noncolicky epigastric pain, es­pecially in the presence of one of the known as­sociated disorders (Table 42-2). The differential diagnosis usually includes biliary colic, a perfo­rated viscus (especially a duodenal ulcer), acute cholecystitis, abdominal vasculitis, acute bowel infarction, renal colic, and a number of other causes of “the acute abdomen.”

Most patients with clinically defined acute pan­creatitis have an enlarged pancreas as defined by ultrasonography and/or CT, but the diagnosis can­not be made without concomitant evidence of aci­nar cell injury as reflected in an elevation of serum amylase. Conversely, other causes of an elevated serum amylase must be considered also (Table 42—3). After the onset of symptoms serum amy­lase rises early (2 to 12 hours) and usually remains elevated for three to five days. Some believe that in the face of an elevated serum amylase, an as­sociated increased renal clearance of amylase (amylase clearance > 4 per cent of that of creat­inine) is a useful indication of the presence of pan­creatitis, but the test is not diagnostic.

Other laboratory abnormalities may include hy­perglycemia, hypocalcemia, and leukocytosis.

Treatment and Prognosis. The treatment of acute pancreatitis is largely supportive: (1) careful monitoring and volume replacement for fluids lost retroperitoneally; (2) relief of pain, preferably using meperidine; (3) nasogastric suction—this traditional approach to “putting the pancreas at rest,” however, will not affect outcome in mild to moderate cases; (4) treatment of complications as they arise—calcium for hypocalcemia, insulin for excessive hyperglycemia, etc. Other measures that have been advocated, including administra­tion of cimetidine, aprotinin, and glucagon, ap­pear to be without benefit.

About 90 per cent of patients recover, usually within one to two weeks. About 10 per cent die despite therapy, most frequently from the adult respiratory distress syndrome or from shock.

Complications. The complications most fre­quently seen in the course of acute pancreatitis are listed in Table 42-4. A phlegmon is a solid mass of inflamed pancreas, which usually sub­sides spontaneously. A pseudocyst is a liquified collection of necrotic debris surrounded by a rim of pancreatic tissue and/or other tissue. Small pseudocysts may disappear, but large ones may persist to cause pain or bleeding, erode into ad­jacent tissues, or become infected, requiring sur­gical drainage.