Patency of femorofemoral venous crossover grafts assessed by duplex scanning and phlebography

This study was undertaken to determine the accuracy of duplex imaging of femorofemoral venous crossover grafts (Palma-Dale operation) for postthrombotic unilateral occlusion of the iliac vein. Twenty-four patients, 14 men and 10 women with a mean age of 50 years (range 24 to 72 years), were subjected to duplex imaging and phlebography a mean of 5 years after surgery. Scanning was done with patients in an erect position. A graft was reported as patient if it met the following criteria: it could be imaged in continuity, it could be compressed by the scan probe, and blood flow varied with respiration and was augmented by thigh compression on the symptomatic side. Phlebography indicated that 20 grafts were patent and 17 of these were correctly identified with duplex scanning. Three scans were false negative in obese patients in whom the graft could not be imaged. Four grafts, not imaged, were confirmed by phlebography to be occluded. Compared with phlebography, duplex scanning had a sensitivity of 85%, specificity of 100%, and overall accuracy of 88%. Duplex scanning is safe and accurate way to determine patency after femorofemoral venous bypass if the criteria for patency are fulfilled. If not, the true status of the graft must still be established by phlebography.