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 What can an abdominal ultrasound Detect? 25/01/2022 What happens if you eat and drink before an abdominal ultrasound? 25/01/2022 Can I have coffee before an abdominal ultrasound? 25/01/2022