Investigations

The investigations of choice in cholecystitis are:

• FBC – usually shows leucocytosis
• liver function test – to detect any obstructive jaundice (1)
• abdominal x-ray:
  • can reveal radio-opaque stones in minority of cases
  • may show air in the biliary tree
  • can rule out intra-abdominal free air – seen in diverticulitis or perforated peptic ulcer (2)
• ultrasound:
  • recommended for any suspected acute cholecystitis
  • first-choice imaging method for the morphological diagnosis of acute cholecystitis (3)
  • diagnosis of acute cholecystitis is made radiologically when the following are present at the same time:
    • thickening of the gallbladder wall (5 mm or greater)
    • pericholecystic fluid
    • ultrasonographic Murphy’s sign
      • pain which occurs when the probe is pushed against the gallbladder
      • superior to ordinary Murphy’s sign (3)
  • other findings may include: gallbladder enlargement, gallbladder stones, debris echo and gas imaging (3)
• magnetic resonance cholangiopancreatography (MRCP):
  • can obtain images of the whole of the biliary tree and adjacent structures
  • small stones can be detected
  • recommended if abdominal ultrasound does not provide definitive diagnosis (3)
• CT scan:
  • finding may include: gallbladder distention (41%), gallbladder wall thickening (59%), pericholecystic fat density (52%), pericholecystic fluid collection (31%) (3)
  • recommended for diagnosing gangrenous cholecystitis and emphysematous cholecystitis (3)
• radio-isotopic scanning – HIDA scanning:
  • has a sensitivity of 80–90% for acute cholecystitis
  • normally outlines the gall bladder and duct system
  • if gallbladder is obstructed, cannot take up contrast, hence, not shown
  • ‘rim sign’ (a blush of increased pericholecystic radioactivity) is present in about 30% of patients with acute cholecystitis and in about 60% with acute gangrenous cholecystitis (3)
  • usually reserved for patients in whom diagnosis is unclear after ultrasonography (4)

Reference:

1. Dawson J. Acute cholecystitis. GPonline 2009
2. Elwood DR. Cholecystitis. Surg Clin North Am. 2008;88(6):1241-52
3. Yokoe M, et al.Tokyo Guidelines 2018: diagnostic criteria and severity grading of acute cholecystitis (with videos). J Hepatobiliary Pancreat Sci. 2018 Jan;25(1):41-54. doi: 10.1002/jhbp.515. Epub 2018 Jan 9. PMID: 29032636.
4. Strasberg SM. Clinical practice. Acute calculous cholecystitis. N Engl J Med. 2008;358(26):2804-11.