This is usually not necessary, but if a digestive system test is to be done, fasting is required. Clinically, fasting is required when doing examinations of the liver, gallbladder, pancreas, spleen, and gastrointestinal tract. Due to the interference of the contents of the gastrointestinal tract, especially the gas, the cut that the doctor wants to examine is not displayed properly or incompletely, and it is possible to miss or misdiagnose some of the lesions. Clinically speaking, fasting is generally required to fast after eight o’clock the night before and to abstain from water after ten o’clock. And it is to get up in the morning without water, medication or food for the examination. If the examination includes gallbladder examination, it is better to eat a light diet the day before, forbid to eat some gas-producing foods and avoid foods with high fat content. Gastrointestinal examination is basically the same as liver, gallbladder, pancreas and spleen examination, but gastrointestinal examination is not only to understand the sonographic changes in the stomach during fasting, but also to compare and observe the sonogram after filling and expansion of the stomach cavity, so as to evaluate the structures and functions of the stomach and intestines. It is advisable to ask the medical staff of the ultrasound department in advance of the ultrasound examination whether the item you are examining requires pre-test preparation or not.