RESUMO
BACKGROUND: The increasing use of vena cava filters by trauma surgeons has led to reports of filter placement using intravascular ultrasound (IVUS). Although attractive because of its ease of use and elimination of contrast and radiation, no studies have examined the accuracy of filter placement by IVUS as compared with contrast venography (CV). The purpose of this study was to compare the anatomic information obtained by both techniques during filter placement. METHODS: Twenty-one patients meeting trauma service criteria for filter placement were studied (11 women and 10 men; mean age, 46.8 years). All procedures were performed in the operating room by trauma surgeons. Vascular access was obtained by percutaneous placement of an 8 French sheath in the right femoral vein. CV, IVUS, and bilateral selective renal venography were performed before deployment of a Greenfield filter. Localization and diameter measurements were made in reference to a radiopaque ruler placed on the patient's abdomen. We chose the "best location" for filter deployment as 1 cm below the junction of the lowest renal vein and the vena cava. Measurements by CV and IVUS were compared with the "gold standard" of selective renal venography. RESULTS: As compared with selective renal venography, the difference between best location by CV and IVUS was 16.3 +/- 13.8 mm and 3.7 +/- 5.6 mm, respectively (p = 0.001). In four cases (19%) the CV missed best location by 3 cm or more. CV overestimated the diameter of the vena cava in all cases. Average vena cava diameter was 26.4 +/- 3.3 mm by venography and 20.6 +/- 3.1 mm by IVUS (p < 0.0001). CV incorrectly identified four patients as having vena cava diameters too large (>2.8 cm) for the placement of a Greenfield filter. The two renal vein anomalies (one double left renal vein and one absent left renal vein) were correctly diagnosed by IVUS. CONCLUSION: IVUS is a more accurate method of localizing the renal veins and measuring vena cava diameter for placement of vena cava filters than contrast venography.