Doppler and Colour Flow

Many machines have colour flow as standard. It works on the Doppler principle and takes thousands of small gates and represents each as a colour.

It is important to check the indicator, often at the top of the screen, to ensure this has not been reversed. The colours do not detect venous and arterial blood unless the probe is angled toward the trunk in which case arterial blood will appear red and venous blood blue in the major vessels.

Colour flow interpretation follows the ‘Bart Simpson rule’ i.e.





This image shows Colour flow depicting an AV fistula in the groin.