Is Fasting required for an abdominal ultrasound? If you are having an abdominal ultrasound, you are required to fast for at least 4 hours. There is a lot of outdated information online, some recommend fasting from 8 to 12 hours. You Might Also Like Can liver disease be detected on an abdominal ultrasound? 25/01/2022 Can I drink Water before an Abdominal Ultrasound? 25/01/2022 What can an abdominal ultrasound Detect? 25/01/2022