1. We recommend use of precise anatomic terminology to characterize the most proximal extent of venous thrombosis as involving the iliofemoral veins, with or without extension into the inferior vena cava; the femoropopliteal veins; or isolated to the calf veins in preference to simple characterization of a thrombus as proximal or distal (Grade 1, Level A).
2. If iliofemoral venous thrombosis is suspected but not confirmed using standard diagnostic modalities such as venous ultrasound imaging, we recommend the use of adjunctive imaging modalities, such as computed tomography venography or magnetic resonance venography to characterize the most proximal thrombus extent (Grade 1, Level C).