Doppler ultrasonography
ultrasound imaging of the movement of tissues and body fluids using the Doppler effect
Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to perform imaging of the movement of tissues and body fluids (usually blood), and their relative velocity to the probe. By calculating the frequency shift of a particular sample volume, for example, flow in an artery or a jet of blood flow over a heart valve, its speed and direction can be determined and visualized.
Duplex ultrasonography sometimes refers to Doppler ultrasonography or spectral Doppler ultrasonography. Doppler ultrasonography consists of two components: brightness mode (B-mode) showing anatomy of the organs, and Doppler mode (showing blood flow) superimposed on the B-mode. Meanwhile, spectral Doppler ultrasonography consists of three components: B-mode, Doppler mode, and spectral waveform displayed at the lower half of the image. Therefore, "duplex ultrasonography" is a misnomer for spectral Doppler ultrasonography, and more exact name should be "triplex ultrasonography".
This is particularly useful in cardiovascular studies (sonography of the vascular system and heart) and essential in many areas such as determining reverse blood flow in the liver vasculature in portal hypertension.
Operation
Colour Doppler shows the direction of the blood flow in red or blue (either towards or away from the transducer). Meanwhile, spectral Doppler not only shows the direction of blood flow, it also shows the phases (pulsatility) and acceleration of the blood flow. Any sudden changes in direction of blood flow produces audible sounds on the ultrasound machine.
“Doppler ultrasonography” enters the record as ultrasound imaging of the movement of tissues and body fluids using the Doppler effect. Crown Archives preserves that source wording while asking what Doppler, ultrasonography and ultrasound can confirm, complicate or overturn.
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Chronology, provenance and viewpoint should be read together before a broad social or political interpretation is accepted. The source revision retrieved here is dated Jun 22, 2026. The linked authority identifier is Q3577488.
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This entry incorporates text from “Doppler ultrasonography” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.