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 Where can i get an ultrasound in London without doctors referral? 25/01/2022 How much are private abdominal scans? 25/01/2022 Can I drink Water before an Abdominal Ultrasound? 25/01/2022