Emphysematous Cholecystitis
Gas in the gallbladder wall (intramural) or lumen on CT = gas-forming organisms (Clostridium, E. coli). Seen in diabetics, elderly, and patients with vascular disease. High mortality (15–25%) — emergent cholecystectomy (percutaneous cholecystostomy if too ill).
Do not confuse with intraluminal gas (normal post-procedure) — intramural gas follows wall contour, is non-dependent, and appears linear or bubbly.
Gangrenous Cholecystitis CT Findings
- Intraluminal membranes (desquamated mucosa — pathognomonic)
- Irregular or asymmetric wall thickening
- Absent or asymmetric wall enhancement
- Pericholecystic fluid and fat stranding
- Discontinuous mucosal line
- Perforation: pericholecystic abscess, free fluid, wall defect
Higher surgical morbidity than uncomplicated cholecystitis.
Diagnosis Reference Table
| Diagnosis | US Findings | CT Findings |
|---|---|---|
| Acute cholecystitis | Gallstones + sonographic Murphy sign; GB wall thickening >3 mm; pericholecystic fluid; GB distension (>5 cm transverse) | GB wall thickening; pericholecystic fat stranding; GB distension; impacted stone in neck/cystic duct; periportal edema |
| Gangrenous cholecystitis | Intraluminal membranes (echogenic strands); absent Murphy sign (denervation); irregular wall; no wall vascularity on Doppler | Intraluminal membranes; wall irregularity/asymmetry; absent wall enhancement; pericholecystic abscess; pneumobilia |
| Emphysematous cholecystitis | Echogenic foci in wall with "dirty shadowing" or ring-down artifact; may obscure GB anatomy | Gas in GB wall (intramural, non-dependent) and/or lumen; pericholecystic gas; may have associated liver abscess |
| Choledocholithiasis | Hyperechoic foci in CBD with posterior acoustic shadowing; CBD dilatation >6 mm (>8 mm post-cholecystectomy); visualized in ~50% by US | Hyperdense foci in CBD on non-contrast; MRCP superior for stones <3 mm; impacted ampullary stone at distal CBD; biliary dilatation |
| Cholangitis (Charcot's / Reynolds pentad) | Biliary dilatation; CBD stones; GB stones; may show periportal edema; abscess formation in severe cases | Biliary dilatation; obstructing stone or stricture; periportal edema; hepatic abscesses (pyogenic); pneumobilia; portal vein thrombosis |
| Gallstone ileus | Distended bowel loops; large ectopic gallstone; biliary-enteric fistula (pneumobilia); cholecystoduodenal fistula | Rigler's triad: SBO + ectopic gallstone + pneumobilia; stone at terminal ileum; Bouveret syndrome = gastric outlet obstruction (duodenal impaction) |
| Mirizzi syndrome | Impacted stone in GB neck/cystic duct causing extrinsic CHD compression; proximal biliary dilatation; contracted GB | Stone impacted at GB neck; fusiform narrowing of CHD at cystic duct level; biliary dilatation above; choledochal fistula in advanced cases (type II–IV) |
Reporting Checklist
- Gallbladder wall thickness (mm; >3 mm abnormal if fasting)
- Sonographic Murphy sign: positive / negative / not assessed
- Gallstones: present / absent; location (neck / body / fundus impaction)
- Pericholecystic fluid / fat stranding: present / absent
- GB distension: transverse diameter (>5 cm abnormal)
- Intraluminal membranes or sloughed mucosa (gangrenous features): present / absent
- Wall enhancement on CT: hyperenhancing / heterogeneous / absent
- Gas in GB wall or lumen (emphysematous): present / absent — surgical emergency
- Biliary dilation: CBD diameter; choledocholithiasis present / absent
References
Shakespear JS et al. CT findings of acute cholecystitis and its complications. AJR. 2010;194(6):1523–9.
Radiopaedia — Acute cholecystitis