Before the ultrasound examination of the liver, gallbladder, spleen and kidney, it is forbidden to drink a lot of water, usually after eating the night before the examination, but the details should be analyzed according to the examination site. The main reason is that the principle of ultrasound is to determine the shape of internal organs through sound transmission and feedback, but after eating or drinking, the gallbladder may be emptied of bile, resulting in blurred observation of the internal structure of the gallbladder, which may lead to errors in the diagnosis of the disease and affect the further treatment. There is no requirement for drinking water if kidney ultrasound or spleen ultrasound is performed, but a lot of water is needed for bladder ultrasound in advance. It is recommended to fast for at least eight hours before the examination. The night before the examination, a light and easily digestible diet is recommended, and gas-producing foods such as soy products should be avoided.