Generally speaking, the stomach is not examined by B-ultrasound, unless the baby spits milk to check whether there is reflux, only the specialist children's hospital can do it. Occasionally, gastric retention in adults can also be detected by B-ultrasound. If you ask for a B-ultrasound of the stomach, the doctor will be dumbfounded. Ultrasound can't detect it because it will disperse the gas in the stomach. The liver can be examined separately without fasting. But generally speaking, the liver and gallbladder will be examined at the same time, and the single liver examination is the same as the simultaneous liver and gallbladder examination. Examination of gallbladder requires fasting for 8- 12 hours, preferably in the morning. So we suggest doing abdominal B-ultrasound on an empty stomach in the morning. Abdominal B-ultrasound includes liver, gallbladder, pancreas and spleen. In principle, only gallbladder emptying is required. But through clinical observation, I found that even if some people don't eat breakfast in the morning, they will still have an impact on the examination because they ate midnight snack or greasy dinner the night before. Some people don't eat supper, but smoke before the examination, or exercise vigorously, talk loudly or sing. It will cause gas to enter the digestive tract in the stomach, interfere with the display of pancreas and left liver, and even affect gallbladder and part of the right anterior lobe of liver. So I suggest that the inspection time should be chosen in the morning, preferably not near noon, and keep quiet before the inspection, don't smoke, and don't talk too much. Similarly, if you want to do abdominal B-ultrasound, gastroscopy or barium meal examination, you must do B-ultrasound first, then gastroscopy or barium meal. If you have done gastroscopy or barium meal, it takes 24 hours to check B-ultrasound. This is my major+experience, I hope it will help you. You can always ask me about the B-ultrasound.