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Acute cholecystitis

Aetiology

Acute cholecystitis is associated with gallstones in over 90 per cent of patients. It follows the impaction of a gallstone in the cystic duct. Continued secretion by the gallbladder leads to a rise in pressure. Inflammation of the gallbladder wall results from the toxic effects of the retained bile and bacterial infection. The gallbladder bile is usually turbid but may become frank pus (empyema of the gallbladder). Intestinal organisms, especially anaerobes, are commonly cultured from the gallbladder. Ischaemia in the distended gallbladder wall may lead to infarction and perforation. Generalized peritonitis may follow, but the leak is usually localized to form a chronic abscess cavity. Some patients have repeated attacks of acute cholecystitis which are probably exacerbations of chronic cholecystitis. Acute cholecystitis in the abscence of gallstones (acalculous cholecystitis) is usually very rare. However, acalculous cholecystitis is a particular problem in patients with the acquired immunodeficiency syndrome (AIDS). Cytomegalovirus and cryptosporidium are the most commonly associated organisms in acalculous cholecystitis in AIDS.

Symptoms and signs

The typical patient is an obese, middle-aged female, and the acute attack is often precipitated by a large or fatty meal. However, there are many exceptions to this pattern. The principal symptom is pain, of fairly sudden onset, which is severe, continuous or minimally fluctuating, and localized to the epigastrium or right hypochondrium. The pain often radiates to the back. The constancy of the pain is in contrast to the repeated short bouts of biliary colic. In uncomplicated cases the pain gradually subsides over 12 to 18 h. Flatulence and nausea are common but persistent vomiting suggests the presence of a stone in the common bile duct. Examination reveals an ill, sweating patient with shallow, jerky respiration. Fever indicates a complicating bacterial cholangitis. Jaundice may accompany acute cholecystitis but is usually a sign of a stone in the bile duct. The abdomen moves poorly with respiration. Right hypochondrial tenderness is present and is exacerbated by inspiration (Murphy's sign). Muscle guarding and rebound tenderness are common. The gallbladder is usually impalpable but occasionally a tender mass of omentum and gallbladder may be felt under the liver.

Laboratory investigations

The white cell count is usually moderately elevated (12 to 15 × 109/l) due to a polymorphonuclear leucocytosis. Serum bilirubin concentrations between 17 and 68 µmol/l (1 and 4 mg/dl) may be seen in uncomplicated acute cholecystitis, but should raise the suspicion of a stone in the bile duct. Modest rises in the serum alkaline phosphatase, aspartate transaminase, and amylase may also be seen. An abdominal radiograph will show gallstones in about 10 per cent of patients. Ultrasound scanning of the gallbladder is the preferred first investigation. Scintiscanning with 99Tcm-labelled HIDA provides similar information. It is important to establish the correct diagnosis before surgery is performed.

Complications

Gangrene of the gallbladder Pain, tenderness, and fever progressively increasing or persisting for longer than 24 to 48 h are indications of gangrene of the gallbladder. The prognosis is poor if necrosis and perforation occur. In patients who are elderly and obese, perforation of the gallbladder can occur without definite signs. Perforation into an adjacent viscus may produce a cholecystenteric fistula and may lead to gallstone ileus.

Cholangitis

Intermittent high temperatures often accompanied by rigors indicate bacterial infection of the bile duct and usually follow the passage of a stone into the bile duct.

Treatment

In most patients acute cholecystitis subsides in a few days with conservative treatment. Cholecystectomy is performed either a few days after the symptoms have settled or 2 to 3 months later. In the latter event, if the symptoms recur during the interval, cholecystectomy is performed without delay. Immediate surgery is mandatory if signs of gangrene or perforation develop.