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CLINICAL REVIEW
Contributed by Mr Joe Dawson, specialist registrar in general surgery, Basildon and Thurrock University Hospitals NHS Foundation Trust
Section 1 Epidemiology and aetiology
Gallstones
Acute cholecystitis (inflammation of the gallbladder) is one of the most common complications of gallstones, although it does rarely occur in the absence of gallstones (acalculous cholecystitis).
Gallstones consist of cholesterol (15 per cent), pigment (5 per cent), or a mixture of the two (80 per cent). The majority of mixed stones contain over 50 per cent cholesterol.
Factors linked to cholesterol stones include female sex and increasing age. Cholesterol stones form when the solubilising capacity of bile is exceeded. Supersaturated cholesterol leads to the formation of cholesterol microcrystals.
Acute acalculous cholecystitis
Acute acalculous cholecystitis may occur as a complication of severe burns or trauma.
The aetiology may be due to blood-borne infection, undetectable biliary sludge or an inflammatory response by the gallbladder to concentrated bile salts.
Acute cholecystitis
If a gallstone remains in the gallbladder it does not cause symptoms - only 10-30 per cent of patients with gallstones will become symptomatic.
However, if the stone impacts in the gallbladder neck or cystic duct, it will result in pain as the gaUbladdercontractsbehindthe blockage. If the stone falls back, the gallbladder empties and the pain subsides (biliary colic).
If the stone remains impacted then trapped bile leads to elevated gallbladder pressure, resultingin reduced gallbladder mucosablood flow.
This results in mucosal damage by bile with a consequential chemical irritation, inflammatory infiltration and oedema of the gallbladder wall.
Possible outcomes are summarised in the box.
Section 2 Diagnosis
When a patient first presents with the principal symptom of acute cholecystitis it may be difficult to differentiate biliary colic from acute cholecystitis. However, the differentiation is important as treatment of the two conditions differs greatly.
Biliary colic
Biliary colic occurs when a gallstone impacts in the neck of the gallbladder obstructing the cystic duct
The pain resolves spontaneously as the stone falls back into thegallbladderorpasses into the common bile duct (CBD). The elevated pressure within the gallbladder due to the temporary blockage leads to sustained gallbladder contraction.
The typical presentation is of sharp, sudden onset right upper quadrant (RUQ) or epigastric pain, radiating under ribs, to the right lower chest, directly...