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 There is a lot of outdated information online, some recommend fasting from 8 to 12 hours.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 How much are private abdominal scans? 25/01/2022 What happens if you eat and drink before an abdominal ultrasound? 25/01/2022 What does red mean on an abdominal ultrasound? 25/01/2022