Investigation of the deep venous system of the lower limb must mainly aim to elucidate its capabilities. Because deep venous incompetence is necessarily con nected with a popliteal reflux accounted for by valvular incompetence of the popliteal vein, its presence must be clarified. An isolated valvular incompetence of the femoral vein without popliteal incompetence is of no clinical significance and should be disregarded. Only patients with popliteal reflux detected by Dop pler ultrasound require a further examination by venous pressure measure ments and by phlebography. An operation in the deep veins is admissible only when a popliteal reflux > 40%, and ambulatory venous pressure > 60 mmHg, a refilling time < 15 sec, a venous insufficiency > 20%, and a patency or recanalization of the deep venous > 70% have been confirmed. A correlation between venous pressure and Doppler recordings has been done.
