Diagnosis of DVT on Ultrasound: Compression Test, Signs of Acute and Floating Thrombus, Common Mistakes
Compression Test as the Gold Standard
The compression test is the gold standard for diagnosing DVT. A normal vein completely collapses under transverse compression, whereas a vein with a thrombus does not. Compress strictly in the transverse plane, perpendicular to the skin, every 1–2 cm along the entire length of the vessel. Duplex scanning (DUS) remains the primary method of choice for venous diseases, providing assessment of anatomy, patency, venous wall condition, and blood flow.
Echographic Signs of Acute Thrombus
Main echographic signs of a thrombus:
- visualization of an echogenic structure in the vein lumen;
- non-compressibility of the vein upon compression;
- passive dilation of the vein diameter.
The evolution of a thrombus over time and differentiation between acute and chronic processes are critically important: the response determines the strategy (anticoagulation for fresh DVT or management of old post-thrombotic changes). [clarification needed: specific echocriteria for acute vs chronic thrombus over time are not fully provided in the fragments]
Floating Thrombus
[clarification needed: specific criteria for floating thrombus are not provided in the source fragments]
Examination Protocols
| Protocol | Scope | Features |
|---|---|---|
| Two-point Compression (CUS) | Only common femoral and popliteal veins | Quick, but misses isolated thrombosis of femoral and tibial veins; sensitivity in inexperienced hands drops to ~57% |
| Extended | From common femoral to popliteal vein | — |
| Complete Compression (CCUS) | From groin to ankle, including tibial veins | — |
Modern multidisciplinary guidelines prefer whole-leg examination, supplemented with color and spectral Doppler with assessment of phasicity and augmentation. Two-point compression is permissible as an express method at the bedside, but with mandatory repeat examination if the result is negative and clinical suspicion persists.
Common Mistakes
The most significant mistakes are associated with the shortened protocol: the two-point test misses isolated thrombosis of femoral and tibial veins, and its sensitivity in inexperienced hands drops to ~57%. If the express examination result is negative and clinical suspicion persists, a repeat examination is mandatory. Compression should be performed precisely in the transverse plane, perpendicular to the skin.
Frequently asked questions
How to correctly perform the compression test?
Compress the vein strictly in the transverse plane, perpendicular to the skin, every 1–2 cm along the entire length of the vessel. A normal vein completely collapses, whereas a vein with a thrombus does not.
Which protocol is preferred when suspecting DVT?
Modern multidisciplinary guidelines prefer whole-leg examination, supplemented with color and spectral Doppler with assessment of phasicity and augmentation.
When is two-point compression permissible?
As an express method at the bedside, but with mandatory repeat examination if the result is negative and clinical suspicion persists.
What are the main echographic signs of a thrombus?
Visualization of an echogenic structure in the vein lumen, non-compressibility of the vein, and passive dilation of its diameter.
Why is the two-point test risky for missing thrombosis?
It covers only the common femoral and popliteal veins, missing isolated thrombosis of femoral and tibial veins; sensitivity in inexperienced hands drops to ~57%.