Medically, the liver, gallbladder, pancreas, and spleen of the human body are clinically called liver, gallbladder, pancreas, and spleen. Color Doppler ultrasound examination requires fasting, because it is an abdominal ultrasound examination , and patients are generally asked to fast for more than eight hours before the examination. Most of them start fasting after dinner the day before and go for the examination the next morning. Ultrasound examinations of the liver, gallbladder, pancreas, and spleen have high requirements for the gastrointestinal tract, because the contents and gas in the gastrointestinal tract will affect the examination results, so it is necessary to fast as much as possible. If the patient usually has abdominal distension or severe constipation, he can also do corresponding enema treatment before the examination, which can make the examination conditions better.

Color Doppler ultrasound examination is more accurate for observing the patient's bile duct system when the patient is not eating. For the gallbladder, when the stomach is fasting, the bile in the gallbladder is in a state of congestion. Generally, the structure of the gallbladder is clearer through color Doppler ultrasound, and it is more accurate to further judge whether the patient has polyps and stones in the gallbladder, and whether the gallbladder wall is rough.

If the patient is undergoing a renal ultrasound examination, there is no need to fast. The kidney is one of the parts of the urinary system that can be examined. If you want to do a bladder or prostate examination, you need to hold your urine, but there is no special requirement for fasting. It is just that they are all part of the abdominal organs and are easily affected by the gas in the intestine. Therefore, patients with abdominal distension should also try to fast for renal ultrasound examinations, so that the effect of the examination may be better, but they do not need to fast for such a long time.