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Unlike arterial ultrasonography, venous ultrasonography is carried out with the probe in a transversal position, (perpendicular to the vein axis), displaying cross-sections of the veins. [4] All collateral veins are better detected this way, including perforator veins, but of most importance is the detection of venous thrombosis.
Doppler measurements which trace the echoes of the generated soundwaves received by the probe, enable the direction and velocity of the blood flow to be depicted. The overlay of color onto the Doppler information lets these images be seen more clearly. [8] The choice of a probe will depend on the depth needed to be studied.
Depending on the type of angiogram, access to the blood vessels is gained most commonly through the femoral artery, to look at the left side of the heart and at the arterial system; or the jugular or femoral vein, to look at the right side of the heart and at the venous system.
Absence of the portal system in a first trimester case associated with hygroma and aorto-umbilical fistula. (A): Transverse plane of the upper abdomen with color Doppler applied, showing umbilical cord insertion, stomach, the prominent hepatic artery and no afferent liver venous perfusion; (B): midsagittal plane reconstructed from a three-dimensional volume acquisition were the crown-rump ...
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound.
Venous refill with dependency (should be less than 30 seconds) – the vein should bulge outward within 30 seconds of elevation for one minute. Buerger's test (assessment of arterial sufficiency): With the patient supine, note the colour of the feet soles. They should be pink. Then elevate both legs to 45 degrees for more than 1 minute.
The venous system returns the de-oxygenated blood to the right heart where it is pumped into the lungs to become oxygenated and CO 2 and other gaseous wastes exchanged and expelled during breathing. Blood then returns to the left side of the heart where it begins the process again.
Lower limb venography is indicated in deep vein thrombosis, oedema with unknown cause, and congenital abnormality of the venous system. Less frequently it is used to demonstrate the incompetent valves of perforating veins. Doppler ultrasound is preferable rather than venography to access the competence of the veins.