Diagnosis

Duplicated inferior vena cava

Findings

Contrast-enhanced computed tomography (CT) of the chest demonstrates extensive mural thrombus within the pulmonary arteries (Figure 1). Contrast-enhanced CT of the abdomen reveals duplication of the inferior vena cava (IVC) with drainage of the left IVC into the left renal vein (Figures 2 and 3). Venocavography confirms absence of a left iliac vein inflow defect as well as faint opacification of the left renal vein and a left-sided IVC (Figure 4).

Discussion

IVC filters serve to prevent significant pulmonary embolism in cases of venous thromboembolism, in which standard medical therapy is inappropriate or inadequate. Specifically, well-accepted indications for filter placement include thromboembolism complicated by failed anticoagulation (documented progression/recurrence despite anticoagulation), chronic pulmonary thromboembolism, contraindication to anticoagulation (active gastrointestinal bleeding, recent surgery or intracranial hemorrhage, vascular central nervous system metastases), and complications of anticoagulation.¹

Variant anatomy of the IVC and its tributaries is relatively common and often has significant clinical implications, particularly for filter placement planning. Duplication of the IVC represents one of the more common IVC variants (0.2% to 3%)² and results from failed regression of the left supracardinal vein during embryogenesis. Rather than crossing midline to join the right iliac vein, the left iliac vein continues vertically as a left IVC, which subsequently drains to the left renal vein. Other common variants include circumaortic left renal vein, retroaortic left renal vein, and mega cava. Preprocedural cross-sectional imaging, if available, should be reviewed during treatment staging.

Inferior venocavography in cases of duplication will typically demonstrate absence of a left iliac vein inflow defect. Occasionally, retrograde contrast will identify the duplicated IVC as it enters the left renal vein. Prominent communicating pelvic venous moieties are often present. If the routine cavogram is ambiguous, catheterization of the left renal vein is recommended to confirm or exclude duplication.¹

Treatment options include placement of bilateral infrarenal IVC filters or a single suprarenal filter. Although the later has been historically considered suboptimal due to a theoretical increased risk of renal vein thrombosis, recent data suggests that suprarenal filter placement is both safe and effective.³

1. Valji K. The practice of interventional radiology. Philadelphia, PA: Elsevier Saunders; 2012.
2. Bass JE, Redwine MD, Kramer LA, et al. Spectrum of congenital anomalies of the inferior vena cava: Cross-sectional imaging findings. Radiographics. 2000;20:639-652.
3. Kalva SP, Chlapoutaki C, Wicky S, et al. Superior inferior vena cava filters: A 20-year single-center experience. J Vasc Interv Radiol. 2008;19:1041-1047.