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Ultrasonography of chronic venous insufficiency of the legs; Duplex evaluation is usually done prior to any invasive testing or surgical procedure. [8] Ultrasound duplex scanning can provide additional information that may guide therapeutic decisions. The location and severity of arterial narrowings and occlusions can be identified.
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.
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.
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.
A duplex ultrasound (doppler ultrasonography and b-mode) can detect venous obstruction or valvular incompetence as the cause, and is used for planning venous ablation procedures, but it is not necessary in suspected venous insufficiency where surgical intervention is not indicated. [10] [6]
On duplex ultrasound, demonstration of echogenic material within the portal vein, complete or partial absence of colour flow in the portal vein, presence of collateral vessels around the portal vein or gall bladder that bypass the portal vein. [9] Portal vein thrombosis grading after Yerdel et al
The use of ultrasonography in a medical application was first used in the late 1940s in the United States. This use was soon followed in other countries with further research and development being carried out. The first report on Doppler ultrasound as a diagnostic tool for vascular disease was published in 1967–1968.
The term duplex refers to 2 modes of ultrasound scanning being conducted. The B-mode transducer allows for an image of the vessel to be obtained, providing visual cues on the extent of occlusion. Meanwhile, the doppler probe is used to acquire data on velocity and direction of blood flow. [39]