Diagnostics

• Initial evaluation: laboratory studies and RUQ ultrasound (consider biliary POCUS if available)

• If ultrasound findings are inconclusive, consider HIDA scan, abdominal MRI, or abdominal CT to confirm the diagnosis.

• Assess for choledocholithiasis

• Once the diagnosis is confirmed, determine the severity

• CBC: Leukocytosis is most common, but WBC count may be normal in up to 40% of patients.

• CRP: elevated

• Blood cultures: should be obtained, especially in patients with grade III acute cholecystitis

• Bile cultures: should be obtained in patients undergoing laparoscopic cholecystectomy or gallbladder drainage

• Blood gas analysis: PaO2/FiO2 ratio < 300 in severely ill patients

• BMP: AKI, electrolyte derangements may be present in patients with severe disease

• PT/INR: coagulopathy in patients with severe disease

should be obtained in all patients with suspected cholecystitis

• LFTs [14][16]

  • Mild elevations in AST and ALT are possible in acute cholecystitis.

  • Signs of cholestasis (↑ bilirubin, ↑ ALP, ↑ GGT) are uncommon in cholecystitis; if present consider biliary obstruction (see ''Diagnosis of choledocholithiasis'' and ''Cholangitis'')

• Lipase, amylase

  • Mild elevation of amylase may be seen in acute cholecystitis [17]

  • Elevation of lipase or amylase ≥ 3 times the normal is suggestive of acute biliary pancreatitis.

• Indications: preferred initial imaging modality in suspected acute cholecystitis [9][10]

• Characteristic findings [10]

  • Gallbladder wall thickening > 3–5 mm [7]

  • Gallbladder distention (8–10 x 4 cm) [10][18]

  • Gallbladder wall edema (double-wall sign): The innermost and outermost layers appear hyperechoic; edematous tissue appears as a hypoechoic layer in between.

  • Sonographic Murphy sign: Tenderness upon compression of the gallbladder with the ultrasound transducer

  • Pericholecystic free fluid

  • Presence of gallstones and/or biliary sludge

  • In emphysematous cholecystitis, mural air appears as hyperechoic shadows within the gallbladder wall.

• Important consideration: The CBD should be assessed for choledocholithiasis (see ''Diagnosis of choledocholithiasis” for further details).

Commonly referred to as hepatobiliary iminodiacetic acid scintigraphy or a HIDA scan.

• Indications: preferred confirmatory test for suspected uncomplicated acute cholecystitis if ultrasound findings are inconclusive

• Advantages

  • High sensitivity (96%) and specificity (90%); considered the gold standard test to diagnose acute cholecystitis

  • Can differentiate between acute and chronic cholecystitis

• Characteristic findings

  • Normal: gallbladder visualized within 4 hours of administration of radioactive tracer

  • Acute cholecystitis: gallbladder is not visualized within 4 hours

• Indications

  • Alternative to CT or HIDA scan in suspected acute cholecystitis with inconclusive ultrasound findings

  • Either of the following in patients with contraindications to CT:

    • Suspected complications of cholecystitis

    • Clinical diagnosis of acute cholecystitis unclear

  • Suspected choledocholithiasis (MRCP)

• Characteristic findings: Similar to ultrasound findings

• Indications

  • An alternative to MRI or HIDA scan in suspected acute cholecystitis with inconclusive ultrasound findings [9][21]

  • Suspected emphysematous cholecystitis [10]

  • Suspected complications of acute cholecystitis [7][10]

  • Clinical diagnosis of acute cholecystitis unclear [2][7]

• Characteristic findings: similar to those on ultrasound and MRI

• Acute cholangitis

• Liver abscess

• Acute hepatitis

• Acute necrotizing pancreatitis

• Acalculous cholecystitis

• Chronic cholecystitis

• Bile leak (Iatrogenic)

• Biliary colic

• PUD

• Acute gastritis

• Acute pancreatitis

• Chronic pancreatitis

• Acute GERD

• Sphincter of Oddi dysfunction

• Congestive hepatopathy

• Nephrolithiasis

• Malignancy

  • HCC

  • Cholangiocarcinoma

  • Gallbladder cancer

  • Pancreatic cancer