Ultrasound has the highest probability of being used in ultrasound examinations. ultrasound examinations cover a wide range of areas, of which the requirements and preparations are completely different for different parts of the examination. In general, except for upper abdominal examinations, especially liver, gallbladder and pancreas examinations, it is important to prepare for fasting in advance. If you eat something it will cause the gallbladder to contract. There is no way to find out the condition of the gallbladder by doing ultrasound. Eating to do abdominal examination will cause the corresponding lesions to be masked, and this situation greatly increases the probability of missing the diagnosis. Therefore, it is important to fast during the upper abdominal examination. In addition, the genital system of the urinary system and the corresponding hematopoietic tests do not require fasting.