Early experience using duplex ultrasonography in the diagnosis of deep venous thrombosis; a prospective evaluation

Duplex ultrasound is used in many radiology departments as the first line of investigation for symptomatic deep venous thrombosis. Before changing the practice of our department from venography to duplex ultrasonography, we wanted to assess our ability to identify deep venous thrombosis on ultrasound. Thirty-eight patients were investigated for suspected deep venous thrombosis by venography and duplex ultrasound. The results were compared using venography as the 'gold standard'. Duplex ultrasound correctly identified 13 out of 16 limbs with deep venous thrombosis. Four of the 38 duplex ultrasound examinations (11%) were described as inadequate at the time of examination, and when these are excluded from the analysis a sensitivity of 93%, and specificity of 80% are achieved. We conclude that there is a significant learning curve when performing duplex ultrasound of the lower limb, and that change-over from venography to ultrasound should include a period during which both examinations are routinely performed.