Compression sonography

Compression sonography is the sonographic examination of the vein volume for compressibility (Ludwig 2010). It is the method of choice for detecting thrombosis of the extremities (Ludwig 2023).

In compression ultrasonography, the venous lumen of the extremities can normally be fully compressed with the ultrasound probe. In the presence of a thrombus, however, this compression is not possible or only partially possible. However, compression sonography cannot be performed in the abdominal region (Ludwig 2010).

The sensitivity and specificity of the method in symptomatic patients with a thrombosis in the deep sections of a vein are 95 % and 100 % respectively (Ludwig 2010).

If compression ultrasonography does not show a clear result, phlebography is recommended (Ludwig 2010).

If there is a high clinical probability of thrombosis and the sonography is negative at the same time, it is recommended to check the compression sonography after 4 - 7 days (Endres 2025).

- Indications for performing compression ultrasonography:

- Suspected thrombosis, especially deep vein thrombosis of the leg

- Probably also for unclear acute compartment syndrome (however, further studies are required for this [Bloch 2018])

- Performance of compression sonography:

If thrombosis of the lower extremities is suspected, the patient is usually examined in the supine position. If there is a gas overlay, the right or left lateral position is recommended. The affected leg should be slightly externally rotated and slightly flexed at the knee joint.

The popliteal vein is sometimes easier to sonograph in the prone position, whereas the lower leg veins are easier to sonograph with the patient standing or sitting, as the veins are then better filled. However, the increased muscle tone can make compression more difficult (Schäberle 2016).

- Segmental compression sonography:

First, a segmental compression sonography is performed, in which the examination begins with a B-image cross-section. The possible constellations of findings are:

• Easy and fully compressible
• Difficult, but completely compressible
• Vascular segment not compressible at all (Huck 2005)

If the vein is easily compressible, a thrombus proximal to the site of examination is unlikely. If it is difficult to compress, on the other hand, it can be assumed that there is an obstruction to drainage proximal to the site of examination (Huck 2005).

- Offset compression sonography:

The second examination step consists of examining an easily or completely compressible area of the vein proximally and distally in order to define a closer delineation of the compressed area (Huck 2005).

- Examination protocol:

Various examination protocols for compression ultrasonography have been developed and clinically validated, which differ essentially in the extent of the vein segments examined and in the number of examinations required to reliably rule out thrombosis. Duplex-assisted full compression ultrasonography is recommended with

- continuous imaging in cross-section with intermittent probe compression of the:

• Common femoral vein
• Mouth region of the great saphenous vein
• Mouth region of the profunda femoral vein
• Femoral vein
• Popliteal vein
• Mouth region of the saphenous vein
• Fibular veins
• Posterior tibial veins
• Muscular veins of the soleus and gastrocnemius muscles

- Vein visualization in longitudinal section under spontaneous flow conditions and / or compression-decompression of the:

• Vena femoralis communis
• Popliteal vein (Guidelines 2023)

In an emergency room, the so-called two-point CUS (compression ultrasound) has established itself as an acceptable alternative due to the time-consuming nature of the compression sonography described above (Fleischmann 2023).

Color coding can also be used to visualize the part of the thrombus with blood flow. If the vein is completely occluded, Doppler sonography will no longer show any flow (Herold 2020).

Compression sonography can be used for thrombi of the femoral vein, popliteal vein, posterior tibial vein, fibular vein and anterior tibial vein. If thrombosis of the iliac vein is suspected, the venous flow signal in the femoral vein should also be checked and documented (Ludwig 2023).

During sonography of the shoulder arm veins, compression sonography is only possible distal to the axillary vein (Guidelines 2023).

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