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 There is a lot of outdated information online, some recommend fasting from 8 to 12 hours.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 I drink Water before an Abdominal Ultrasound? 25/01/2022 What happens after the examination? 25/01/2022 How much are private abdominal scans? 25/01/2022