Venous ultrasounds are highly accurate, non-invasive diagnostic tests used to detect blood clots, vein blockages, and valve dysfunction within the venous system. By combining standard ultrasound imaging with Doppler technology, this test visualizes both the structure of veins and the movement of blood through them in real time. For diagnosing deep vein thrombosis (DVT) in the legs, venous ultrasound has been shown to have a sensitivity of 94–97% and a specificity of 93–97%, making it one of the most reliable imaging methods available. These high percentages mean the test is very effective at correctly identifying the presence or absence of a clot, especially in larger veins above the knee.

Accuracy can vary depending on factors such as the location of the clot, operator expertise, and the patient’s anatomy. Ultrasounds are most reliable for detecting clots in the thigh and pelvis, while smaller calf veins can be harder to assess with the same precision. For conditions like chronic venous insufficiency, venous ultrasound also demonstrates excellent accuracy—often near 95–100%—when performed by experienced technicians. Because it’s safe, painless, and widely available, venous ultrasound is considered the gold standard for initial vein evaluation and ongoing monitoring of venous disease or treatment effectiveness.