Acute right lower extremity iliofemoral deep venous thrombosis secondary to an anomalous inferior vena cava: a report of two cases.

A congenital anomaly of the inferior vena cava is an increasingly identified risk factor for iliocaval deep venous thrombosis in young patients. We present two cases of acute right lower extremity iliofemoral deep venous thrombosis in 16 and 18-year-old patients that were ultimately diagnosed with an underlying anomalous iliocaval venous system. In one patient, the inferior vena cava was congenitally absent and the right iliac vein was diffusely stenotic with a proximally located high-grade stricture. In the other subject, the infrarenal inferior vena cava and right iliac vein were diffusely hypoplastic. Compensatory venous flow in both subjects was via large perilumbar venous collateral veins and a prominent azygous system. Both patients were successfully treated with a combination of initial catheter-directed thrombolysis followed by balloon angioplasty and venous stent placement.