Doppler ultrasonography helps determine which parameter of blood flow?

• A. Pulmonary artery pressure
• B. Nerve conduction velocity
• C. Blood flow velocity
• D. Heart chamber size

Answer: (C)

Doppler ultrasonography is all about how fast blood is moving through vessels. It uses the Doppler effect—the change in frequency of ultrasound waves reflected off moving red blood cells—to quantify the speed (velocity) and direction of blood flow along the line of insonation. This makes it the tool of choice for assessing how quickly blood is moving, detecting abnormalities like stenosis (increased velocity through narrowed areas) or turbulent flow. The other options aren’t what Doppler directly measures: pulmonary artery pressure is a pressure value, nerve conduction velocity is an electrical measure of nerves, and heart chamber size is a structural dimension typically assessed with standard ultrasound imaging rather than Doppler flow velocity.