Ultrasound of the hepatobiliary system requires an empty stomach. It is also best to eat a light and oily diet the day before, and to fast after 8:00 pm and water after 10:00 pm the night before. Liver examinations are relatively less affected by diet, but biliary system examinations are required to fast for at least eight hours. If there is no fasting, there is no guarantee that the gallbladder and bile ducts are in a state of filling, because eating will cause contraction of the gallbladder and bile ducts, resulting in a reduction in the volume of the gallbladder, thickening of the gallbladder wall, and poor display of the gallbladder wall and lumen, then the lesions in the gallbladder and bile ducts will not be clearly displayed, making it difficult to make a clear diagnosis of the disease. Moreover, after eating, gastric contents and gas in the stomach and intestine can interfere with the partial view of the liver and the gallbladder and bile duct system. Therefore, for some patients it is necessary to perform an enema and bowel movement before the examination. For patients who need X-ray gastrointestinal imaging, ultrasound should be arranged first, followed by a barium meal X-ray. Most hepatobiliary ultrasound examinations require fasting, but for emergency patients, they are not subject to the above conditions and can be performed in a timely manner under close observation.