What tool is commonly used to assess blood flow velocity?

The ultrasound transducer is the correct tool commonly used to assess blood flow velocity. It emits pulses of ultrasound waves which travel through the body and are reflected back by moving blood cells. This interaction provides critical information about the speed and direction of blood flow. Using techniques such as Doppler ultrasound, clinicians can determine the velocity of blood flow in vessels, which is essential for diagnosing various cardiovascular conditions.

In contrast, an echocardiogram is a specific type of ultrasound that focuses on the heart's structure and function rather than directly measuring blood flow velocities in vessels. Venography is an imaging technique used to visualize veins using a contrast agent, primarily for identifying blood clots, but it does not provide real-time flow velocity data. An electrocardiogram, on the other hand, records the electrical activity of the heart, providing information about heart rhythms but not about blood flow velocity itself.