What does red mean on an abdominal ultrasound? The red and blue colours on the screen during your ultrasound in London indicate the direction of blood flow. You can read more about Doppler ultrasound Imaging. You Might Also Like Can I drink Water before an Abdominal Ultrasound? 25/01/2022 Can liver disease be detected on an abdominal ultrasound? 25/01/2022 Can I have coffee before an abdominal ultrasound? 25/01/2022