Which ultrasound technique uses high-frequency sound waves directed at blood vessels?

Doppler ultrasound is the technique that employs high-frequency sound waves to assess the flow of blood within blood vessels. This method takes advantage of the Doppler effect, which refers to changes in frequency or wavelength of sound waves in relation to an observer moving relative to the source of the sound. When sound waves are directed at moving blood cells, the frequency of the reflected waves changes based on the speed and direction of blood flow. This allows clinicians to visualize and measure the velocity of blood flow, thereby helping in the diagnosis of vascular conditions, assessing cardiac function, and evaluating blood flow in various organs.

In contrast, other ultrasound techniques serve different purposes. 3D ultrasound is primarily utilized for creating three-dimensional images of structures, which is especially useful in obstetrics and certain diagnostic situations but not specifically for blood flow assessment. Transvaginal ultrasound involves inserting a transducer into the vagina to obtain detailed images of female reproductive organs, having a different focus that does not include blood vessel analysis. Endoscopic ultrasound combines endoscopy with ultrasound to visualize and obtain images from within the gastrointestinal tract, typically looking at the organs and surrounding tissues rather than blood flow specifically.