Distribution of thrombi in acute lower extremity deep venous thrombosis: Implications for sonography and CT and MR venography

OBJECTIVE, Our objective was to determine the typical distribution of throm bi in acute lower extremity deep venous thrombosis as a means of evaluating the validity of imaging techniques that only include the common femoral an d popliteal veins, but not the superficial femoral vein, MATERIALS AND METHODS. The results of 2704 lower extremity venous sonograms , obtained in 2026 consecutive patients over a 4-year interval, were review ed retrospectively, The distribution of acute deep venous thromboses across various lower extremity venous segments was analyzed for this population, which consisted of both symptomatic and asymptomatic patients. RESULTS. Of 2704 lower extremities studied with duplex sonography, acute de ep venous thrombosis was identified in 269 (9.9%). Of these 269 cases, acut e deep venous thrombosis was isolated to the superficial femoral vein in 60 (22.3%). The remaining 209 cases (77.7%) showed thrombus that extended int o the common femoral or popliteal veins (or both). CONCLUSION. An abbreviated imaging study that evaluates only the common fem oral and popliteal veins would fail to identify more than 20% of lower extr emity acute deep venous thromboses in a population like ours. Although eval uation of the superficial femoral vein requires additional rime and resourc es, evaluation of this segment may prevent a substantial number of thrombi from being missed.