[Role of Doppler echography in the diagnosis of venous thrombosis].

The diagnosis of deep vein thrombosis (DVT) by non-invasive techniques is usually based on the haemodynamic changes detected by doppler ultrasound and plethysmography. These two investigations are not very sensitive in the diagnosis of non-occlusive proximal thrombosis or distal (infrapopliteal) and isolated thromboses. Ultrasonic Duplex Scanning (B mode and Doppler) is a new method of investigation of DVT which visualises the anatomy of the veins and surrounding structures and also provides assessments of the venous circulation. The diagnosis of DVT is made on the finding of an abnormal endoluminal image, the absence of venous compressibility and doppler changes. Duplex ultrasonography differentiates DVT from extrinsic compression, enables diagnosis of even nonocclusive or isolated proximal thrombosis irrespective of its site and of distal thrombis. The site, extension and age of the thrombosis may also be estimated. It is very competitive with phlebography and is even superior in some indications. This method has been evaluated mainly in patients with clinically suspected DVT. The mean values of diagnostic sensitivity and specificity compared with phlebography are over 95% in the examination of popliteal and femoral veins; iliac veins, inferior vena cava and calf veins have correctly rarely been studied but with good results: the sensitivity of diagnosis of distal DVT is approximately 90%. Duplex ultrasonography is a non-invasive, cost-effective and reliable method which is widely used, though requiring further validation both in the diagnosis of symptomatic and asymptomatic DVT and its surveillance. The diagnostic value of the investigation is operator dependent and is also influenced by the equipment and protocol of examination. The value of color flow imaging has not yet been well established.