What do colors in a renal ultrasound mean?

Ultrasound: Color is used to determine whether a blood vessel is an artery or vein. If you saw colors on your kidney ultrasound, it means a "doppler" was done to look at the blood vessels. With a doppler, everyone will gave color (blue and red).

Doppler: A regular ultrasound shows shades of black and white to identify kidney sizes and structures. A doppler senses flow to (red) and from (blue) the probe. Doppler ultrasound is used to rule out renal artery stenosis and venous obstruction in the kidneys.