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 it easy to book an abdominal ultrasound appointment? 25/01/2022 Can you see gastritis on an ultrasound? 25/01/2022 Can I drink Water before an Abdominal Ultrasound? 25/01/2022