Accurate determination of inferior vena cava (JVC) size before filter
placement is of outmost importance in order to avoid fitter migration espe
cially 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 JVC meas
urements obtained using a gold standard technique and two other widely
accepted methods, and (b) if differences exist, how often do these differ
ences cause incorrect JVC sizing around a diameter of 28 mm.
Twelve inferior vena cavograms were retrospectively evaluated. The
transverse diameter of the infrarenal JVC was determined by using a cali
brated intravascular catheter (method 1), subtraction of 20% from the
measured transverse JVC diameter on a cut-film radiograph (method 2),
and a radiopaque ruler placed immediately posterior to the patient (meth
od 3), The concordance correlation of methods 2 and 3 versus method 1
were 90.9 % and 81.8% respectively to determine agreement at an JVC di
ameter of 28 mm.
In conclusion, inferior vena cavegraphy prior to JVC filter placement
should be performed with a calibrated intravascular catheter, as the two
other formerly accepted methods of determining IVC diameter, that is, the
20% magnification rule, and use of an external measuring device are un
reliable and result in high incidence of technically false results. |
