The WES triad -- a specific sonographic sign of gallstones in the contracted gallbladder.

The "WES" triad -- that is, the demonstration of the gallbladder Wall, the Echo of the stone, and the acoustic Shadow -- permits the specific diagnosis of stones in a contracted gallbladder. This triad positively identifies the gallbladder and helps to differentiate the contracted gallbladder with stones from a loop of bowel containing gas.