Doppler ultrasound or echo-Doppler is a non-invasive diagnostic test based on a conventional ultrasound (image in two dimensions, in gray scale), using ultrasound (sounds below the human auditory spectrum) to which is associated a flow wave that is obtained by taking advantage of the Doppler effect (like a sonar from a submarine).
The Doppler effect is the translation into graphics of an ultrasound beam that collides with the moving elements in its path (the formed elements of blood: red blood cells, white blood cells, platelets, etc.) and returns another beam that the computer transforms into a graphic (wave). It is also called “duplex”, and if we associate color to the particles in movement we obtain the “triplex”. Conventionally, everything approaching the probe will be represented in red, and everything moving away in blue.
How is Doppler ultrasound performed?
The patient will discover the area to be explored; the specialist in Angiology and Vascular Surgery, depending on the type of exploration, will invite the patient to stand or lie down, face up or face down, as well as with different turns of the neck. He/she will spread a “transducer” gel and pass a probe (like a microphone) over the area to be examined.
What are the applications of echo-Doppler?
The specialist will perform this test to explore flows, their speed and direction (hemodynamics), as well as to obtain data on the shape and size of the vessel being analyzed (morphology).
Thus, in the arterial sector he will analyze:
- TSA Duplex: the characteristics of the vessels that irrigate the brain, plaques, ulcers, stenosis, obstructions; the flow velocity and its variations with the neck positions. Useful in carotid stenosis (stroke prevention), carotid elongations, aneurysms, vertebral artery stenosis, vertigo analysis, subclavian artery stenosis,…
- Abdominal duplex: visceral trunks, renal arteries, aneurysms and stenosis of the aorta or iliac arteries.
- Duplex of lower extremities: in chronic ischemia (claudication, rest pain, injuries), aneurysms.
- Viability analysis of flaps for microsurgical reconstruction of the head and neck, in all territories, exploring the existence of perforating arteries, location, viability of the donor area.
In the venous sector:
- Diagnosis of deep or superficial venous thrombosis.
- Venous insufficiency and varicose veins
- Aneurysms
- Malformations
Patient preparation for Doppler ultrasound?
The patient, except for abdominal Doppler ultrasound, does not require fasting or any other preparation, except, perhaps, to wear comfortable clothes that are easy to take off and put on.
Risks of Doppler ultrasound
As we have said, it is a non-invasive test, that is to say, there are no injections to be made, no canals to be cannulated, and no contrasts that may produce an allergic reaction or damage to any organ.
If the color Doppler ultrasound (triplex) has not been diagnostic, it will use an “echo-enhancer”, via vein, based on a sugar, which does not produce an allergy, but which should be used with caution in diabetic patients. But this test is performed on an exceptional basis.