In Color Doppler, which color indicates flow toward the transducer?

• A. Red toward
• B. Blue away
• C. Green toward
• D. Yellow toward

Answer: (A)

Color Doppler uses color to show both the direction and speed of blood flow relative to the transducer. The common convention is that red indicates flow toward the transducer, while blue indicates flow away. The shade or brightness of the color reflects velocity—the brighter the red, the faster the flow toward the transducer. Note that some ultrasound systems can invert this mapping, but red-toward is the typical standard you’ll encounter. The other colors listed aren’t the usual directional code for toward flow; they may appear for other reasons (like turbulence or different color maps) but they don’t represent toward in the standard convention.