Fig. 7
From: The inferior vena cava: anatomical variants and acquired pathologies
Absent infrarenal IVC with azygos continuation. Paired common iliac veins continue cranially as bilateral ascending lumbar veins. a Contrast-enhanced coronal CT demonstrates the caudal end of the IVC (asterisk). b Coronal CT shows the right ascending lumbar vein (arrow) approaching and subsequently draining into the IVC (asterisk). Tortuous paravertebral collateral veins (arrowhead) are present adjacent to the aorta. c Axial CT image with left renal vein (arrow) crossing anterior to the aorta to drain into the renal IVC segment (asterisk). Right renal vein (arrowhead) also approaches renal IVC segment. d Axial CT shows prominent bilateral ascending lumbar veins (arrowheads) and a distended paravertebral collateral (arrow) positioned left of the aorta