[Computerized tomography in the follow-up of inferior vena cava filters]

CT was employed to evaluate IVC filters in 37 patients; most devices (25) were Greenfield filters. Filters were localized below the renal veins in 26 patients; a suprarenal position was observed in 11 cases. Filter malpositioning was shown by CT in 1 case (filter partially located in the left renal vein); migration of the device into left pulmonary artery was detected in 1 patient. IVC perforation occurred in 11 cases--in 6 of them, the filter penetrated into adjacent structures (duodenum in 2 cases, abdominal aorta in 2, liver in 1, and right kidney in 1 patient). IVC thrombosis was seen in 16 patients; complete caval obstruction developed in 2 cases two or more years after filter positioning. IVC perforation caused by a filter is a frequent complication (30% of our series), but in most cases it is asymptomatic and has no significant clinical relevance; surgical removal of the filter had to be performed in 3 cases only. CT scanning is a valuable adjunct to plain abdominal radiography in the follow-up of IVC devices, when a complication (especially IVC perforation) is suspected.