Vena cava umbrella filters, employed to treat pulmonary embolism, are usually positioned at the level of the inferior pole of the right kidney as determined from intravenous pyelography (IVP).
Using inferior cavography to define caval anatomy, we found anomalies in two of ten patients (single left inferior vena cava, double inferior vena cava). One patient, in whom an umbrella was previously placed at the level of the inferior pole of the right kidney, developed recurrent pulmonary emboli from the cul-de-sac between the occluded umbrella and the right renal vein; a second umbrella was placed. In another patient, postplacement vena cavography identified umbrella obstruction of the right renal vein; repositioning with a second umbrella was successful.
Combined vena cavography and umbrella placement allows (1) visualization of inferior vena cava, including anomalies; (2) precise placement of umbrella filter; (3) occasional detection of source of emboli; and (4) confirmation of diagnosis of pulmonary embolus.
Douglas McConnell, Donald Mulder, Gerald Buckberg. The Placement of Vena Cava Umbrella FiltersThe Value of Phlebography. Arch Surg. 1974;108(6):789–791. doi:10.1001/archsurg.1974.01350300031008