Venous diagnostics and, in particular, ultrasound examination (sonography) of the venous vessels play a major role in the diagnosis and treatment of diseases of the venous vascular system. The field of application includes above all the exclusion of venous thrombosis (occlusion of the vein by a blood clot) and the detection of insufficient venous valves (venous valves enable the flow of blood through the veins back to the heart by preventing reflux, e.g. into the legs, if the valves are destroyed this leads to blood stasis), which can lead to dangerous complications if treatment is not carried out. Both the examination procedure and the technical options are explained below.
Indications (areas of application)
- Visualization of venous angiomas (vascular malformation).
- Detection of venous thrombosis in both arm and leg veins
- Evidence of saphenous vein cross insufficiency (congestion in the area where the saphenous vein joins the deep venous system)
- Evidence of perforating vein insufficiency.
- Evidence of deep venous insufficiency or venous valve insufficiency.
- Classification of venous valve insufficiency (primary or secondary).
- Preliminary examination for varicose vein sclerotherapy (sclerotherapy of varicose veins).
- Preliminary examination for compression therapy
- Preliminary examination during venous surgical procedures
The procedure
The performance of ultrasound diagnostics on the venous system depends primarily on the indication. Different ultrasound devices are used for the diagnosis of thrombosis or venous insufficiency. The following technical procedures are available for venous diagnostics:
- CW Doppler sonography-Continuous-wave (CW) Doppler sonography represents a subset of single-channel Doppler techniques. The device is used to determine or dynamically visualize high flow velocities. This procedure is particularly useful for diagnosing venous valve insufficiencies by detecting reflux flow (unwanted blood flow away from the heart).
- Two-dimensional ultrasound – This ultrasound procedure is a conventional sonography, which serves to produce two-dimensional cross-sectional images of the veins. During the so-called compression sonography, the venous vessel or its lumen is examined for compressibility. The procedure is used to diagnose venous thrombosis and has a high degree of accuracy. A thrombosed vein section is hardly or even not compressible.
- Duplex sonography (= combination of B-scan with PW Doppler/Pulse Wave Doppler) – This ultrasound examination is a combination of a two-dimensional ultrasound procedure and Doppler sonography (Doppler sonography is a sonographic procedure that can dynamically visualize fluid flows (especially blood flow)). Duplex sonography allows the diagnosis of venous valve insufficiency and the detection of thrombi and their spatial localization.
- Color duplex sonography – This procedure is functionally similar to duplex sonography described earlier, but a technical change allows color imaging of flow so that turbulence or reflux flow can be more clearly visualized. Color duplex sonography is used primarily for venous vessels in the lower leg.
Diseases of the venous vascular system play out mainly in the lower extremity (eg, lower legs). Less frequently, pathological processes can be detected in the arm veins or abdominal veins (veins in the abdomen). The following findings may be detected by sonography of the veins:
- Venous dilatation – e.g., due to congestion caused by venous reflux.
- Venous thrombosis
- Reflux flows due to insufficient venous valves.
The course of the examination is now illustrated on the venous system of the leg: Knowledge of the exact anatomy of the veins on the leg is a prerequisite for the examination. Both the deep (invisible) and superficial venous systems are separated and thoroughly examined systematically from proximal (near the trunk) to distal (far from the trunk). Subsequently, the perforating veins that connect the two systems are also visualized. The course of the veins determines the patient positioning, which allows optimal accessibility and visualization of the veins.Thus, the deep venous system is examined with the patient lying down and the superficial one with the patient standing. Each venous segment in itself requires special techniques and in-depth knowledge:
- Femoral vein – To rule out venous reflux, the so-called Valsalva test can be used: the patient is instructed to increase abdominal pressure by pressing without allowing air to escape from the mouth and nose. Healthy venous valves withstand the pressure and blood does not flow back into the legs. If insufficient venous valves are present, pathologic blood return can be detected by Doppler sonography.
- Popliteal vein (popliteal vein) – To access the continuing femoral vein, the patient must be in the prone position with the ankle joints elevated. To provoke a flow murmur, the physician may apply manual compression above or below. This involves applying great force to compress the leg muscles and stop the venous blood (proximal compression) or accelerate it (distal compression).
- Lower leg veins – Compression maneuvers can also be performed here.
- V. saphena magna – To visualize this vein of the superficial system, the patient is asked to stand and the vessel is visited on the inner thigh and examined along its entire course. Here, the Valsalva test is also used to detect venous reflux.
- V. saphena parva – This vein is also examined on the standing patient.
- Vv. perforantes – These veins are divided into Cockett, Boyd and Dodd veins, visited by palpation (palpation) and examined with the ultrasound scanner.
Various examination methods are also available for ultrasound examination of the arm and abdominal veins, which are not discussed in detail here.
Benefits
Ultrasonography of the veins is essential for the diagnosis of venous insufficiency and venous thrombosis. As a noninvasive procedure, venous diagnosis is a gentle procedure for the patient and provides the examining physician with valuable information about the condition of the venous vessels.