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Ultrasound of superficial veins of lower limb
Last reviewed: 19.10.2021
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Ultrasonic dopplerography of superficial veins
Examination for venous insufficiency
Although venous valves can be visualized by ultrasound, the diagnosis of venous insufficiency is based on indirect signs. Because proximal pressure increases when the patient performs Valsalva or manual compression, the physician attempts to register a distal reflux signal that is normally prevented by venous valves. Complete varicose veins begin with a failure at the level of the terminal valve and progress with time to distal levels. As a result, the blood filling the superficial weakened veins comes from the deep vein system. When the proximal pressure increases (for example, with a Valsalva test), the deep vein valves close if the deep venous system is maintained, resulting in reflux only between the superficial vein and the proximal proximal deep venous valve. This segment can be quite large in the case of a large saphenous vein, but in the popliteal vein there are so many valves that the volume of reflux is very small. As a result, it is much more difficult to detect varicose veins in the small saphenous vein than in the large one.
The most proximal insolvent valve is the proximal reflux point or the proximal border of venous insufficiency. The first well-balanced valve of the varicose vein is the distal reflux point. The proximal and distal reflux points allow the classification of subcutaneous vein varicose. The proximal reflux point usually consists of a nonfunctional subcutaneous-femoral valve (full subcutaneous varicose, the level of the distal reflux point determines the severity and location of varicose according to the Hach classification: grade I - proximal femur, grade II - distal femur, degree III - proximal tibia, degree IV - distal shin section A similar three-step classification is used for a small saphenous vein.If the proximal reflux point is distal to the terminal valve, the pod Cutaneous varicose is classified as incomplete.
Ultrasound anatomy
The large saphenous vein starts from the medial edge of the foot, rises anterior to the medial malleolus and runs into the femoral vein about 3 cm below the inguinal ligament. There are options in which a large subcutaneous vein enters the superficial epigastric vein (abnormal proximal termination) or into the femoral vein below the venous fusion (abnormal distal end).
The small saphenous vein begins at the lateral edge of the foot, rises behind the medial malleolus and flows into the popliteal vein 3-8 cm above the joint knee line. The terminal compartment of the small saphenous vein is located subfascially and is not available for study. Usually, the large and small saphenous veins narrow to the periphery (the symptom of the "telescope"). Tubular, not narrowed blood vessels with direct blood flow are a sign of extrafascial collateralization in deep vein thrombosis, whereas a tubular vessel with an inverse blood flow speaks of venous insufficiency. A significant decrease in the rate of blood flow in the untenable veins can cause the presence of spontaneous intraluminal echoes. These echoes disappear when the sensor is pressed.
Methodology of research
The patient is examined in a standard position with relaxed legs. Another option: the leg can be bent and lowered across the edge of the examination table for varicose veins below the knee joint. After the terminal sections of the subcutaneous veins are detected, the proximal pressure on the sensor is increased to assess the functional state of the valves. The sample is repeated on several levels to determine the distal boundary of venous insufficiency. Venous compression is performed proximally during the Valsalva trial, its goal is to decide whether there is a direct deficiency of the subcutaneous veins, or whether there are additional aspects (lack of lateral branches and perforating veins). In patients with incomplete varicose veins, the proximal border of venous insufficiency is thus defined. Insufficiency of perforating veins can be visualized using ultrasound dopplerography. There is no need for bandaging, as with continuous wave Doppler. It is impractical to scan the entire limb for the purpose of finding untenable perforating veins, the study should be limited to clinically suspicious areas (for example, a zone of blisters, typical skin changes).