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 Is Fasting required for an abdominal ultrasound? 25/01/2022 What can an abdominal ultrasound Detect? 25/01/2022 How much are private abdominal scans? 25/01/2022