Vascular surgery Vascular surgery The patency of grafts and anastomoses, for example femoro popliteal bypasses and abdominal aneurysm, needs to be checked by regular clinical assessment of the limbs and by Doppler ultrasound in the postoperative phase. Vascular surgery The patency of grafts and anastomoses, for example femoro popliteal bypasses and abdominal aneurysm, needs to be checked by regular clinical assessment of the limbs and by Doppler ultrasound in the postoperative phase.