Bilateral sign refers to the thickening of the gallbladder wall with edema, and on ultrasonography, the gallbladder wall shows diffuse thickening of the strongly echogenic bands and hypoechogenic bands in the edematous part of the gallbladder wall, which is manifested bilaterally. The main etiologies are acute cholecystitis, chronic cholecystitis, cirrhotic portal hypertension, hypoproteinemia, and right heart insufficiency. The normal gallbladder wall on ultrasonography shows a homogeneous echo surrounding an elliptical cystic cavity, less than three millimeters thick. In edema, the inner diameter can reach four centimeters and the thickness is more than three millimeters. The edematous portion of the gallbladder is hyperechoic due to hypoechoic contrast, while the edges are strongly echogenic. It appears as two parallel bands of strong echoes, also known as the bilateral sign. The cause of bilateral sign is more complicated, timely consultation, identify the cause of the disease and standardize the treatment.