Résumé
Accurate determination of inferior vena cava [IVC] size before filter placement is of outmost importance in order to avoid filter migration especially at a diameter of 28 mm [megacava]. High quality inferior vena cavaography is mandatory to accomplish this. The purposes of this study were to [a] determine if significant differences exist between IVC measurements obtained using a gold standard technique and two other widely accepted methods, and [b] if differences exist, how often do these differences cause incorrect IVC sizing around a diameter of 28 mm. Twelve inferior vena cavograms were retrospectively evaluated. The transverse diameter of the infrarenal IVC was determined by using a calibrated intravascular catheter [method 1], subtraction of 20% from the measured transverse IVC diameter on a cut-film radiograph [method 2], and a radiopaque ruler placed immediately posterior to the patient [method 3]. The concordance correlation of methods 2 and 3 versus method 1 were 90.9% and 81.8% respectively to determine agreement at art IVC diameter of 28 mm. In conclusion, inferior vena cavegraphy prior to IVC filter placement should he performed with a calibrated intravascular catheter, as the two other formerly accepted methods of determining IVC diameter, that is, the 20% maqnification rule, and use of an external measuring device are unreliable and result in high incidence of technically false results