Liver ultrasound generally requires fasting for 8 hours or more. Liver ultrasound is a non-invasive test that is widely used in the clinic for screening of liver and gallbladder related diseases due to its simplicity and low cost. The main reason for doing liver ultrasound on an empty stomach is to obtain more accurate results. If the fasting time is insufficient, there may be a higher content of fat droplets in the liver or contraction of the gallbladder due to the stimulation of undigested food in the gastrointestinal tract, which may lead to errors in the results of liver and gallbladder ultrasound, misdiagnosis, or omission of diagnosis. Therefore, in order to maximize the accuracy of liver ultrasound results, the patient should strictly follow the doctor’s instructions and actively make the relevant preparations before the examination.