What is the typical appearance of a vein under Doppler ultrasound in the presence of thrombosis?

In the presence of thrombosis, a vein typically appears non-compressible under Doppler ultrasound. This characteristic is due to the formation of a clot within the venous lumen, which prevents the vein from collapsing when pressure is applied during the ultrasound examination. Unlike healthy veins that can be easily compressed, a thrombosed vein remains distended and retains its shape, indicating the presence of a clot that obstructs blood flow.

The non-compressibility of the vein serves as an important diagnostic criterion in identifying deep vein thrombosis (DVT). During the ultrasound examination, when gentle pressure is applied to the probe, a normal vein would compress easily, allowing for the assessment of blood flow. However, if the vein is non-compressible, it raises suspicion for thrombosis.

Other appearances, such as being uniformly echogenic or exhibiting high-velocity flow, are not consistent with thrombosis. A uniformly echogenic appearance may suggest chronic changes or other pathological processes rather than the immediate presence of a clot. High-velocity flow is associated with arterial assessments, not veins, and would not indicate thrombosis in this context.