May Be Caused by

 Common

Biliary sludge

Debris

ERCP

Gallstone

Oral cholecystography

 Uncommon

Empyema of gallbladder with pus

Feces via fistula

Food particles after cholecystojejunostomy

Gallbladder hydrops

Gallbladder papilloma

Gallbladder polyp

Hemobilia

Hemorrhagic cholecystitis

Milk of calcium bile

Mucinous adenocarcinoma of gallbladder

Vicarious excretion of contrast medium

Volume averaging with adjacent structures