Patients must be fasting for liver function tests and for medical examinations when blood is drawn. The liver function test is a biochemical test, which generally uses quantitative analysis to determine the biochemical composition of the patient’s blood. If the patient eats and drinks, it will cause trace changes in the blood and serum, and the value of the results will be inaccurate. Therefore, for patients undergoing physical examination, especially those who have their blood drawn for liver function, they should be careful not to drink alcohol and not to eat too oily or spicy or stimulating food for three days before bleeding, so as to maintain a stable state of the body’s environment. The liver function after fasting blood sampling is more accurate and can reflect the liver function in the body. In addition, the patient may need further ultrasound, which will look at the condition of the patient’s biliary system, especially the gallbladder. If the patient eats or drinks water, it will cause the excretion of bile in the gallbladder, and the structure of the gallbladder cannot be seen clearly after excretion. In addition, after the patient eats or drinks, it will cause the gas in the intestine to increase, which will further affect the state of the patient’s liver and biliary tract and other organs.