Colour Doppler is a type of non-invasive, radiation-free ultrasound technique that is used for the estimation of velocity and direction of the blood flow through the blood vessels in real-time.

A Doppler study has the following types: Colour Doppler, Power Doppler, Spectral Doppler, Duplex Doppler and Continuous-wave Doppler.

A Colour Doppler ultrasound study is mainly useful to the health care provider to find out pathologies affecting or blocking the normal blood flow in the body.

Due to its dynamic and real-time properties, Colour Doppler ultrasound can be used to examine both arteries and veins.

It can be used to monitor cardiac function in association with electrocardiogram, look for venous thrombosis in the case of deep vein thrombosis (DVT), detection of varicose veins to check for the incompetence of venous valves, to check patency of arterio-venous fistula in patients of dialysis, to check for arterial occlusions in cases of peripheral arterial disease (PVD) and carotid artery stenosis, check for renal artery stenosis in cases of acute hypertension, to check for portal veins thrombosis by performing a portal Doppler.

A Colour Doppler study is also used in pregnancy to check for fetoplacental or uteroplacental insufficiencies.