Bowel gas can obscure the pelvic organs, which in turn can interfere with the abdominal ultrasound, and there will be no way to see it accurately. Abdominal ultrasound is an ultrasound that examines the abdominal and pelvic organs, and involves a number of organs. Patients examining the gallbladder, liver, pancreas and other parts of the body must be fasting during the examination, and the time of fasting is around 8 hours. The purpose of this is to ensure that there are no obstacles in the intestines to block the ultrasound and that it can be viewed more clearly. If you go for an abdominal ultrasound without fasting, you will be disturbed by the intestinal gas that is created by swallowing food. In addition, there are patients who need to examine the urinary tract and pelvic organs, and these patients need to hold their urine to the extent of holding it until they are conscious of urinating. There are also patients who are undergoing uterine adnexa examination, and these patients must avoid menstruation. These precautions need to ask the doctor, according to their own situation.