Ultrasound (US) is the preferred initial modality in the investigation of right upper quadrant pain. It is more sensitive than HIDA scintigraphy and CT in the diagnosis of acute cholecystitis, and more readily available.
The most sensitive US finding in acute cholecystitis is the presence of cholelithiasis in combination with the sonographic Murphy sign. Both gallbladder wall thickening (>3 mm) and pericholecystic fluid are secondary findings.
Other less specific findings include gallbladder distension and sludge.
Every effort should be made to demonstrate the obstructing stone in the gallbladder neck or cystic duct.
