Obstruction of the inferior vena cava: a multiple-modality demonstration of causes, manifestations, and collateral pathways.

This article explores the causes and manifestations of obstruction of the inferior vena cava (IVC) with a multiple-modality approach. Caval obstruction may be due to thrombus, extension of a tumor, extrinsic compression, or intrinsic caval disease. Evaluation of the IVC should be tailored to the individual circumstance; no single modality is best in all situations. Although magnetic resonance offers multiplanar imaging, vena cavography or ultrasound are often necessary to exclude intraluminal tumor extension. Computed tomography is sensitive for intracaval thrombus and compression but does not delineate the hepatic IVC well. Nuclear venography demonstrates well the resultant collateral pathways, which can be separated into the deep, intermediate, superficial, and portal systems. Despite the clear visualization of these pathways with this modality, congenital caval anomalies, such as caval interruption with azygos continuation, can be confused with acquired caval disease.