A detailed analysis of equivocal duplex findings in patients with suspected deep venous thrombosis.

OBJECTIVE: To analyze equivocal duplex findings in patients with clinically suspected deep venous thrombosis and thus to increase the diagnostic utility of color duplex sonography in this category of patients. METHODS: Phlebography was requested in a series of 102 consecutive patients with inconclusive duplex findings. These patients were, according to the duplex findings only, subdivided into having low, intermediate, and high probability of deep venous thrombosis. RESULTS: Phlebographywas attempted in 71 cases and successfully performed in 49. The remaining 53 patients were prospectively followed clinically for 6 months. Phlebography showed deep venous thrombosis in 1 of 63 patients in the group with low probability, 3 of 31 in the intermediate group, and all of the 8 patients with high probability. Twenty-two (31%) of the 71 attempted phlebographic examinations were nondiagnostic. None of the patients in the follow-up group had any thromboembolic complications. CONCLUSIONS: Even if a duplex examination is equivocal, it is still possible to extract clinically useful information by categorizing the duplex results into subgroups with low, intermediate, and high probability of deep venous thrombosis. This can have implications for the diagnostic or therapeutic handling of these patients and thus can increase the utility of sonography in patients with inconclusive duplex findings.