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 There is a lot of outdated information online, some recommend fasting from 8 to 12 hours.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 What does fatty liver look on ultrasound? 25/01/2022 What can an abdominal ultrasound Detect? 25/01/2022 Can I drink Water before an Abdominal Ultrasound? 25/01/2022 Where can i get an ultrasound in London without doctors referral? 25/01/2022