Diagnostic Ultrasound - Abdomen and Pelvis

Acute Calculous Cholecystitis
TERMINOLOGY
Abbreviations
• Acute cholecystitis
Definitions
• Acute inflammation of gallbladder (GB) secondary to
calculus obstructing cystic duct
IMAGING
General Features
• Best diagnostic clue
○ Impacted gallstone in cystic duct
○ Gallbladder wall thickening
○ Positive sonographic Murphy sign
○ Pericholecystic collection
• Location
○ Stone impacted in GB neck or cystic duct
• Morphology
○ Distended GB is more rounded in shape than normal
pear-shaped configuration
Ultrasonographic Findings
• Grayscale ultrasound
○ Uncomplicated cholecystitis
– Gallstones ±impaction in GB neck or cystic duct
– Diffuse GB wall thickening (> 4-5 mm)
□ Variants: Uniform sonolucent middle layer (halo) or
striated edema
– Hazy delineation of GB wall with echogenic
pericholecystic fat
– Positive sonographic Murphy sign:Pain and
tenderness with transducer pressure over gallbladder
– GB distension with AP diameter > 5 cm
– Sludge inside GB
○ Complicated cholecystitis
– Gangrenous cholecystitis: Asymmetric wall thickening,
marked wall irregularities, intraluminal membranes
– Gallbladder perforation: Defect in GB wall with
pericholecystic abscess or extraluminal stones
– Emphysematous cholecystitis: Gas in GB wall/lumen
– Empyema of gallbladder: Highly reflective intraluminal
echoes without shadowing, purulent exudate/debris
Radiographic Findings
• Radiography
○ Insensitive for cholecystitis; 10-20% of stones are
radiopaque
• ERCP
○ No filling of GB
○ Sharply defined filling defect in contrast-filled lumen of
cystic duct
CT Findings
• CECT
○ Uncomplicated cholecystitis
– Gallstones inside GB neck or cystic duct
– GB wall thickening with subserosal edema
– Increased mural enhancement
– Pericholecystic fat stranding, pericholecystic fluid
– Regional hepatic hyperemia
○ Complicated cholecystitis
– Decreased or absent enhancement
– Discontinuous wall thickening with intramural or
pericholecystic abscesses
– Gas in lumen &/or wall of GB
– High attenuation in GB lumen from hemorrhage/pus
or membranes
MR Findings
• T1WI
○ Hyperintense sludge or hemorrhage in GB
• T2WI
○ Uncomplicated cholecystitis
– Distended GB
– Lower signal stones and sludge
– High signal in thickened wall and pericholecystic
tissues
○ Complicated cholecystitis
– Discontinuous wall thickening with intramural or
pericholecystic abscesses
• T1WI C+
○ Decreased or absent enhancement in complicated
cholecystitis
• MRCP
○ Low signal obstructing stone
Nuclear Medicine Findings
• Hepatobiliary scan
○ Tc-99m iminodiacetic acid derivatives
○ Nonvisualization of GB at 4 hours has 96% specificity
○ Increased uptake in gallbladder fossa during arterial
phase due to hyperemia in 80% of patients
○ "Rim" sign seen in 34% of patients is due to increased
uptake in gallbladder fossa
Imaging Recommendations
• Best imaging tool
○ US is first-line
○ HIDA after equivocal US, more sensitive than US
○ CT and MR for complicated cholecystitis
• Protocol advice
○ Move patient to confirm impacted GB stone, assess
Murphy sign and surrounding area
DIFFERENTIAL DIAGNOSIS
Acute Acalculous Cholecystitis
• Signs of acute cholecystitis without gallstones
• Systemic illness, sepsis
Nonspecific Gallbladder Wall Thickening
• Negative sonographic Murphy sign
• Stones may be present
• Clinical evidence of underlying etiology: Congestive heart
failure, hypoalbuminemia, cirrhosis, regional inflammation
such as hepatitis, pancreatitis
Gallbladder Sludge/Echogenic Bile
• Nonshadowing
• No GB wall thickening or pericholecystic collection
• Negative sonographic Murphy sign
Diagnoses: Biliary System
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