Chronic occlusion mimicking agenesis of the inferior vena cava in patients with iliofemoral deep vein thrombosis.

Agenesis of the inferior vena cava (IVC) has been described as a risk factor for proximal deep vein thrombosis (DVT). We have described the cases of two patients with iliofemoral DVT who had developed post-thrombotic syndrome (PTS). Both cases were misdiagnosed as IVC agenesis on routine imaging; however, an IVC lumen was successfully identified and recanalized during venography with significant improvement in the patients' PTS symptoms. Patients with iliocaval segment DVT with a misdiagnosis of IVC agenesis might have chronic occlusion imitating agenesis. It is worthwhile to attempt percutaneous recanalization of the IVC lumen in these patients and restoring normal venous flow to prevent the development of PTS.