This is a video of a proximal femoral vein valve in longitudinal view. Valves are thin, linear and partially mobile structures that do not prevent venous coaptation. One source of DVT misdiagnosis is visualization of venous valves, which can look like chronic DVT. However, these low level gray tones within the vein caused by rouleaux flow may initially be concerning for an occlusive or nearly occlusive acute DVT. As long as the vein is fully compressible, as shown here, there is no blood clot. This is called rouleaux flow, which is a French word that literally translates into roll. When this happens, you can sometimes visualize the blood cells swirling around each other on 2D black and white ultrasound, as shown in this video.

Sometimes due to proximal obstruction, compression, dehydration, or a hypercoagulability disorder, blood cells in the affected leg approach stasis. In this video, you can see the bright chronic clot inside the black lumen and the vein is partially compressible due to the shrunken clot. In this superficial vein, you can see a partially occlusive and thus partially compressible chronic clot adhered to the wall. Notice how this non-compressible great saphenous vein, or GSV, has become quite small due to the presence of a chronic clot.Ĭompare that to a more recently formed GSV clot, which appears black, relatively dilated and non-compressible. Superficial veins follow the same guidelines for acute or chronic diagnosis. This is an example of a non-obstructive chronic wall scarring from DVT that is no longer significantly obstructing blood flow or at risk of thromboembolization. In long view, a recanalized vein with chronic DVT appears as a bright area that is partially surrounded by color as the shrunken clot allows for partial venous flow. This leads to either scarring of the vein walls or it can result in the vein recanalizing, which means the vein partially reopens and develops increasing compressibility over two to six weeks.Ĭhronically occluded veins sometimes shrink to very small caliber vessels, but often chronic DVTs result in a partially compressible vein as the clots shrink, as you can see in this video.

When the clot becomes more chronic, it appears brighter or whiter on ultrasound and often shrinks. In this case, do not perform a distal augment as there may be potential for the clot to dislodge and cause a PE. With acute occlusive DVT when the clot completely blocks the vein, no color will fill the vein, as shown on this longitudinal color view image. This technologist pressed so hard that the artery completely compressed but the vein still did not.

After two weeks, the clot is considered subacute for a short while and then increasingly chronic with time, during which it either resolves or increasingly adheres to the vein walls, becoming much less of an embolization risk.Īcute DVT, as seen in this transverse image of the femoral vein, appears as a gray or black dilated lumen that is not compressible, as seen in this post-compression image. Regarding potential to cause of pulmonary embolus, or PE, it is for the first two weeks after DVT formation that the clot is considered acute and at risk of embolizing to the lungs.

If the vein is partially or non-compressible, there is DVT there and we can further evaluate from the images whether the clot is acute or chronic. If the vein is compressible, as seen in this video, there is nothing blocking the lumen. The mainstay of deep vein thrombosis or DVT studies is the compression of the deep veins.

Leg ultrasound for dvt