Laboratory Studies
No single laboratory test is diagnostic of a mucocele. However, laboratory workup should include all tests performed for acute cholecystitis. Typical findings include the following:
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A mild leukocytosis with a shift to the left is common; higher counts indicate the possibility of acute cholecystitis or infected bile
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Bilirubin levels are usually within the reference range; they may be mildly raised in patients with Mirizzi syndrome or those with associated common bile duct (CBD) obstruction or cholangitis
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Liver enzymes are usually within the reference range, though a mild rise in alkaline phosphatase may be present; any large increase should raise the suspicion of an obstructed CBD
Ultrasonography
Ultrasonography (US), though entirely operator-dependent, is extremely sensitive in detecting stones in the gallbladder. A grossly distended, thin-walled gallbladder measuring more than 5 cm across anteroposteriorly, an impacted stone in the infundibulum or neck of the gallbladder or in the cystic duct, and clear fluid content indicate a possible mucocele (see the images below). The ultrasonographic Murphy sign may be positive.
Stone in neck of gallbladder, with postacoustic shadowing. Minimal wall thickening and dilated gallbladder suggest mucocele.
Transverse scan shows stone in neck of gallbladder, with postacoustic shadowing. Minimal wall thickening and dilated gallbladder are also visible.
Cluster of impacted calculi in neck of gallbladder, minimal wall thickening, and clear content; this indicates mucocele of gallbladder.
Cluster of calculi with postacoustic shadowing in neck of gallbladder, normal wall, and clear content; this indicates mucocele of gallbladder.
The wall may be thickened, and a small amount of pericholecystic fluid may be present in patients with acute cholecystitis (see the first and second images below). Gross wall thickening and murky, thick fluid with sediments and a pericholecystic collection suggest an empyema or pyocele of the gallbladder (see the third image below). US is also useful in identifying ductal obstruction and is extremely sensitive in identifying intrahepatic biliary tree dilatation. [2, 4, 7]
Image is from a 35-year-old woman who presented with recurrent episodes of right upper quadrant colic; most recent attack was 3 days before. Gross wall thickening is apparent; this is usually measured on anterior wall of gallbladder. Also apparent are clear content, stone in neck of gallbladder, and absence of pericholecystic fluid. All favor diagnosis of acute cholecystitis.
Transverse scans show layering of gallbladder wall; this suggests edema and indicates acute cholecystitis.
Longitudinal scan shows layering, with fluid in wall of gallbladder and impacted stone in neck of gallbladder. Intraluminal shadowing indicates sediments in fluid; image indicates acute cholecystitis with possible pyocele of gallbladder.
Other Imaging Studies
Plain radiography of the abdomen may show a soft-tissue–density shadow with an intraluminal calcific shadow in the subhepatic region. By itself, this finding is nonspecific; it should be used only as a guideline in the differential diagnosis.
Scintigraphy (hepato-iminodiacetic acid [HIDA] scanning) may be indicated in obscure cases, though it can offer only indirect evidence. Nonvisualization of the gallbladder indicates an obstructed gallbladder and possible acute cholecystitis; nonvisualization in the small intestine indicates CBD obstruction.
Computed tomography (CT) may be indicated in cases where the diagnosis is unclear or where there are other associated conditions or complications that must be assessed. The gallbladder is well visualized on CT scanning, and the wall and contents are readily assessed; however, stones may be difficult to identify. The best use of CT may lie in the evaluation of associated hepatic conditions, pancreatitis, and complications such as abscess formation or perforation of the gallbladder.
Magnetic resonance cholangiopancreatography (MRCP) clearly shows the biliary-pancreatic tree, and it is increasingly being used in place of diagnostic endoscopic retrograde cholangiopancreatography (ERCP) to assess the biliary tree. Cholecystokinin (CCK)-enhanced studies are more specific.
Occasionally, percutaneous injection of contrast into the mass may be carried out to identify anatomic details.
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Image is from a 35-year-old woman who presented with recurrent episodes of right upper quadrant colic; most recent attack was 3 days before. Gross wall thickening is apparent; this is usually measured on anterior wall of gallbladder. Also apparent are clear content, stone in neck of gallbladder, and absence of pericholecystic fluid. All favor diagnosis of acute cholecystitis.
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Stone in neck of gallbladder, with postacoustic shadowing. Minimal wall thickening and dilated gallbladder suggest mucocele.
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Transverse scan shows stone in neck of gallbladder, with postacoustic shadowing. Minimal wall thickening and dilated gallbladder are also visible.
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Transverse scans show layering of gallbladder wall; this suggests edema and indicates acute cholecystitis.
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Longitudinal scan shows layering, with fluid in wall of gallbladder and impacted stone in neck of gallbladder. Intraluminal shadowing indicates sediments in fluid; image indicates acute cholecystitis with possible pyocele of gallbladder.
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Cluster of impacted calculi in neck of gallbladder, minimal wall thickening, and clear content; this indicates mucocele of gallbladder.
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Cluster of calculi with postacoustic shadowing in neck of gallbladder, normal wall, and clear content; this indicates mucocele of gallbladder.
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Distended gallbladder with evidence of adhesions on its wall. Irregular surface indicates recurrent attacks of cholecystitis.
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Yellowish aspirate from gallbladder of a 28-year-old woman who presented with features of right upper quadrant peritonitis. Slightly yellowish fluid was sterile and was rich in cholesterol.
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Subserosal perforation of acute, emphysematous, acalculous cholecystitis in a 58-year-old diabetic man. Patient presented with features suggestive of ileus. He had high intrathoracic liver (and gallbladder), and clinical signs were atypical. Green color is unusual.
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Laparoscopic view of distended gallbladder in woman aged 70 years with sudden onset of severe right upper abdominal pain.
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Stone being extracted from cystic duct through small ductotomy.
