Lower limb deep venous thrombosis: a critical view of ultrasound.

The replacement of venography with ultrasound in investigation of lower limb deep venous thrombosis (DVT) is a trend that generally has been appropriate. However, there is substantial variation in reported accuracies related to different clinical contexts, operator experience and sophistication of equipment. The best and most consistent results are for suspected acute femoropopliteal thrombosis, while there is variation in accuracy and diagnostic approach for below knee thrombosis. Potential exists for substantial diagnostic inaccuracy for suspected recurrent DVT, in surveillance of high-risk patients and in patients with possible pulmonary embolism. The choice of ultrasound over contrast venography should take account of local expertise and accuracy, availability of resources, clinical indication for investigation and cost-effectiveness.