Doppler Ultrasound in the Diagnosis of Venous Thrombosis

Abstract

Deep vein thrombosis (DVT) has known morbidity and mortality. New noninvasive techniques such as B-mode scanning and Doppler ultrasonography (duplex) are highly accurate in the diagnosis of this problem but are relatively expensive and time consuming. Continuous-wave Doppler, a precursor noninvasive technique, is simple, cheap, and easy to perform at the patient's bedside. To test the effectiveness of this technique the authors prospectively studied patients with clinical suspicion of DVT by Doppler ultrasound and compared the results with those from venography.

During fourteen consecutive months, patients with a clinical suspicion of DVT underwent continuous-wave Doppler examination of both inferior limbs. Each case was diagnosed as positive, negative, or inconclusive. In addition, the patients underwent a questionnaire regarding risk factors, symptoms, and mean relevant physical findings. Doppler examination was blinded to venography results.

A total of 116 patients with clinical suspicion of DVT were examined by Doppler ultrasound. Their mean age was fifty-five years (range: eighteen to eighty-eight). There were 57 men and 59 women, and from this group a total of 40 patients underwent both Doppler ultrasound examination and venography in the course of forty-eight consecutive hours. When cases with an inconclusive result were excluded, Doppler ultrasound showed a sensitivity of 89%, a specificity of 100%, and an accuracy of 94% for the diagnosis of DVT when compared with venography. When a similar analysis was done for the proximal named veins, continuous-wave Doppler examination showed a very high specificity and positive predictive value and a moderate sensitivity and negative predictive value. (continued on next page)

In the entire group of patients with a Doppler ultrasound examination (n=116), 48 cases had a positive study. Prolonged bed rest, previous surgery, and previous DVT were the most frequent risk factors, pain and swelling the most frequent symptoms, and edema and tenderness the main clinical signs. In patients without DVT (n=57), trauma, malignant obstructing tumors, and cellulitis were the most frequent final diagnoses. The study was inconclusive in 11 patients.

In conclusion, continuous-wave Doppler is accurate and may be used as the initial technique in the diagnosis of DVT. Cases that are inconclusive, or cases in which clinical findings are in evident contradiction to Doppler findings, should undergo duplex examination or venography.