What color is displayed when blood flows away from the transducer, resulting in a lower frequency?

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

Answer: (B)

The correct answer is blue. In the context of Doppler ultrasound, colors are used to indicate the direction of blood flow relative to the ultrasound transducer. When blood is moving away from the transducer, it results in a decrease in frequency, which is represented by the color blue on the Doppler color map. This phenomenon is based on the Doppler effect, where sound waves are compressed or stretched depending on the motion of the source relative to the observer.

In medical imaging, the use of specific colors such as red and blue helps in distinguishing between the flow towards the transducer (often shown in red) and the flow away from it (represented in blue). Understanding this color coding is crucial for interpreting Doppler ultrasound images accurately, as it helps clinicians assess blood flow dynamics and identify potential abnormal conditions.