Placement of dual bird's nest filters in an unusual case of duplicated inferior vena cava.

The authors describe an unusual variant of inferior vena cava duplication, with azygos continuation of the right vena cava and hemiazygos continuation of the left vena cava, discovered at cavography in a patient with pulmonary embolism. Following unsuccessful attempts to advance titanium Greenfield filters through tortuous iliac veins, bilateral Bird's Nest filters were placed successfully.