Patients do abdominal ultrasound need to fasting how long, mainly depends on the specific parts of the examination, as follows: 1, patients do liver, gallbladder, pancreas, spleen ultrasound, generally require patients to fasting for more than eight hours. The main purpose of fasting is to make the patient’s gallbladder completely filled with bile, which is conducive to the display of lesions in the gallbladder, most patients start fasting from the previous day after dinner, the next morning fasting for the examination, the best results, not only able to show the gallbladder, but also to avoid the pancreas, the liver by the gastrointestinal tract contents, the impact of gas. 2, patients do other parts of the abdomen ultrasound, only need to be properly empty stomach can be If the patient’s abdominal distension is obvious, try to fast for a longer time. If the patient does not have abdominal distension or is thin, the fasting time can be shorter.