Acute cholecystitis

Discussion :
Acute Cholecystitis
Etiology:
-(a)in 80-95% cystic duct obstruction by impacted calculus; 85% disimpact spontaneously
-(b)in 10% acalculous cholecystitis

Pathogenesis:
-chemical irritation from concentrated bile, bacterial infection, reflux of pancreatic secretions
Age peak:
-5th-6th decade; M:F = 1:3

persisting (>6 hours) RUQ pain radiating to right shoulder / scapula / interscapular area (DDx: biliary colic usually <6 hours)
nausea, vomiting, chills, fever RUQ tenderness + guarding
leukocytosis, elevated levels of alkaline phosphatase and transaminase and amylase
mild hyperbilirubinemia (20%)
Murphy sign = inspiratory arrest upon palpation of GB area (falsely positive in 6% of patients with cholelithiasis)

Cx:
(1)Gangrene of gallbladder
-shaggy, irregular, asymmetric wall (mucosal ulcers, intraluminal hemorrhage, necrosis)
-hyperechoic foci within GB wall (microabscesses in Rokitansky-Aschoff sinuses)
-intraluminal pseudomembranes (gangrene)
-coarse nonshadowing nondependent echodensities (= sloughed necrotic mucosa / sludge / pus / clotted blood within gallbladder)

(2)Perforation of gallbladder (in 2-20%)
-(a)acute free perforation with peritonitis causing pericholecystic abscess in 33%
-(b)subacute localized perforation causing pericholecystic abscess in 48% (
-c)chronic perforation resulting in internal biliary fistula causing pericholecystic abscess in 18%
Location: most commonly perforation of fundus gallstone lying free in peritoneal cavity sonolucent / complex collection surrounding GB

(3)Empyema of gallbladder multiple medium / coarse highly reflective intraluminal echoes without shadowing / layering / gravity dependence (purulent exudate / debris)