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Low accuracy of color Doppler ultrasound in the detection of proximal leg vein thrombosis in asymptomatic high-risk patients. The RD Heparin Arthroplasty Group.

OBJECTIVE
To evaluate the ability of color Doppler ultrasound to detect proximal deep venous thrombosis (DVT) in asymptomatic high-risk patients who subsequently underwent contrast venography.


DESIGN
Prospective cohort study using blinded observers, with contrast venography as the comparison standard.


SETTING
Seven medical centers (university and community hospitals) participating in a clinical trial of low-molecular-weight heparin for prevention of DVT.


PATIENTS
A total of 385 consecutive patients undergoing elective unilateral hip or knee replacement.


MEASUREMENTS
Ten days after surgery or before hospital discharge (whichever occurred first), patients had bilateral color Doppler ultrasound examinations of the proximal veins of the lower extremities. Subsequently, a contrast venogram of the operated leg was obtained.


RESULTS
Color Doppler ultrasound studies and venograms were both evaluable in 319 of the 385 patients. Deep venous thrombosis was identified by contrast venography in 80 patients (prevalence, 25%; 95% CI, 20% to 30%) and involved the proximal veins in 21 patients (prevalence, 7%; CI, 4% to 10%). For proximal DVT, color Doppler ultrasound showed poor sensitivity (38%; CI, 18% to 62%), moderately good specificity (92%; CI, 89% to 95%), and a poor positive predictive value for this population (26%).


CONCLUSION
Color Doppler ultrasound examinations are insensitive to proximal DVT in asymptomatic high-risk patients and should not be substituted for venography for identifying proximal DVT in such patients.