Investigations of venous disease

Venous thrombosis

Colour Duplex scanning is both sensitive and specific (90 100% in most series) for detecting proximal deep vein thrombosis. Deep veins and arteries lie together in the leg, and the normal vein appears as an echo free channel and is usually larger than the accompanying artery. Venous ultrasonography is a very accurate method ofidentifying deep vein thrombi from the level of the common femoral vein at the groin crease to the popliteal vein but is less reliable for diagnosing calf vein thrombosis.

Criteria for diagnosis of deep vein thrombosis

x Failure of vein to collapse on direct compression
x Visualisation of thrombus within lumen
x Absent or abnormal venous pulsation on Doppler scanning

Venous reflux

Colour duplex scanning has revolutionised the investigation of the lower limb venous system because it allows instant visualisation of blood flow and its direction. Thus, reflux at the saphenofemoral junction, saphenopopliteal junction, and within the deep venous system, including the popliteal vein beneath the knee and the gastrocnemius veins, can be detected without invasive techniques. Although venous reflux can be assessed with a pencil Doppler, this technique misses 12% of saphenofemoral and 20% of saphenopopliteal junction reflux compared with colour duplex scanning.