Duplex ultrasound criteria for diagnosing acute DVT?

• A. Vein noncompressible with echogenic intraluminal material and absence of color flow within the venous segment
• B. Vein compressible with continuous color flow
• C. Vein dilatation with arterial pulsatility
• D. Normal compressibility with increased color flow

Answer: (A)

Duplex ultrasound for acute DVT relies on two key findings: the vein cannot be compressed and there is an intraluminal clot with no blood flow in that segment. When you apply gentle pressure with the probe, a normal vein easily collapses, but a vein with acute thrombus remains stiff and noncompressible because the clot fills the lumen and adheres to the wall. You may also see echogenic material sitting inside the vein, which is the clot itself. Color Doppler adds confirmation by showing an absence of blood flow within that obstructed segment; other parts of the vein may show normal flow, but the affected segment has none. This combination—noncompressibility, intraluminal echogenic material, and lack of color flow within the segment—is the strongest sign of acute DVT on duplex ultrasound.

The other patterns described would not indicate an acute DVT: a compressible vein with continuous color flow suggests patency; a dilated vein with arterial pulsatility points to different vascular issues; normal compressibility with increased color flow also argues against thrombosis.