Which finding is consistent with a diagnosis of acute cholecystitis

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Citation:

Radswiki, T., Vadera, S. Acute cholecystitis. Reference article, Radiopaedia.org. (accessed on 14 Oct 2022) https://doi.org/10.53347/rID-12084

Acute cholecystitis refers to the acute inflammation of the gallbladder. It is the primary complication of cholelithiasis and the most common cause of acute pain in the right upper quadrant (RUQ).

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Acute cholecystitis is a common cause of hospital admission and is responsible for approximately 3-10% of all patients with abdominal pain. Cholelithiasis is the major risk factor and causes up to 95% of cases.14 Other risk factors include AIDS, fibrate use, and ascariasis. 

Constant right upper quadrant pain that can radiate to the right shoulder. Pain typically persists for more than six hours, in contradistinction to the intermittent right upper quadrant pain of biliary colic. Nausea, vomiting, and fever are also often reported.

90-95% of cases are due to gallstones (i.e. acute calculous cholecystitis) with the remainder being acute acalculous cholecystitis.

The development of acute calculous cholecystitis follows a sequence of events:

1. gallstone obstruction of the gallbladder neck or cystic duct
2. inflammation from chemical injury of the mucosa by bile salts
3. reactive production of mucus, leading to increased intraluminal pressure and distention
4. increased luminal distention restricting blood flow to the gallbladder wall (gallbladder hydrops)
5. increasing wall thickness from edema and inflammatory changes
6. secondary bacterial infection in ~66% of patients

Ultrasound (US) is the preferred initial modality in the investigation of right upper quadrant pain. It is more sensitive than HIDA scintigraphy 4 and CT in the diagnosis of acute cholecystitis, and more readily available.

Ultrasound

The most sensitive US finding in acute cholecystitis is the presence of cholelithiasis in combination with the sonographic Murphy sign. Both gallbladder wall thickening (>3 mm) and pericholecystic fluid are secondary findings. 

Other less specific findings include gallbladder distension and sludge.

Every effort should be made to demonstrate the obstructing stone in the gallbladder neck or cystic duct.

Nuclear medicine

HIDA cholescintigraphy in acute cholecystitis will demonstrate non-visualization of the gallbladder 4 hours after injection.  

Cholescintigraphy is unable to demonstrate many complications of cholecystitis, nor the alternative diagnoses which may be found with ultrasound. It is therefore reserved for the evaluation of sonographically equivocal cases.

CT

Although traditionally considered less sensitive than ultrasound, some reviews find CT more sensitive for this diagnosis 12,13,15. An advantage is that CT also allows better evaluation of other pathologies at the same time. CT findings include 3:

• cholelithiasis: gallstones isodense to bile will be missed on CT
• gallbladder distension
• gallbladder wall thickening
• mural or mucosal hyperenhancement
• pericholecystic fluid and inflammatory fat stranding
• high-density bile 15
• enhancement of the adjacent liver parenchyma due to reactive hyperemia
• tensile gallbladder fundus sign 7
  • fundus bulging the anterior abdominal wall
  • ~75% sensitivity and ~95% specificity for acute cholecystitis in the absence of any other CT features
  • useful sign in making an early diagnosis

Diagnostic criteria on CT as proposed by Mirvis et al. include 6:

• major criteria
  • gallstones
  • thickened gallbladder wall
  • pericholecystic fluid collections
  • subserosal edema
• minor criteria
  • gallbladder distention
  • sludge
• diagnosis of acute cholecystitis can be supported if one major and two minor criteria are present refs

MRI

MRI is sensitive in the detection of acute cholecystitis, with findings similar to those seen on ultrasound and CT 3. MR cholangiopancreatography (MRCP) may show an impacted stone in the gallbladder neck or cystic duct as a rounded filling defect.

Treatment and prognosis

Urgent surgical removal of the gallbladder is the treatment of choice for the uncomplicated disease. Gallbladder ischemia with transmural necrosis may occur if the obstruction persists.

Complications

• gangrenous cholecystitis (most common - 20%) 8
• gallbladder perforation (~5%) 8,9
• emphysematous cholecystitis
• pericholecystic abscess
• cholecystoenteric fistula
• cholecystocutaneous fistula 10
• vascular complications (gallbladder hemorrhage, portal vein thrombosis, cystic artery pseudoaneurysm) 11

The differential diagnosis for acute cholecystitis is extensive and includes:

• choledocholithiasis
• pancreatitis
• peptic ulcer disease
• acute hepatitis
• liver abscess
• subhepatic appendicitis

For a more extensive differential, please refer to the article on the differential diagnosis of diffuse gallbladder wall thickening.

• cholecystitis
• chronic cholecystitis
• acute acalculous cholecystitis
• Mirizzi syndrome
• xanthogranulomatous cholecystitis

Related articles: Pathology: Hepato-Pancreato-Biliary

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