In color multispectral ultrasound (CDII), color coding indicates the blood flow side of the question, with red or yellow chromatography indicating blood flow to the probe (hot colors); and blue or blue-green chromatography indicating blood flow to the displaced probe (cold colors). So it does not mean that red indicates arterial blood and blue indicates venous blood. The function buttons on the diagnostic ultrasound instrument allow the diagnostic ultrasound physician to adjust the direction of blood flow at will during the operation in order to facilitate the detection, so the red and blue color is self-adjustable.