Congenital absence of the inferior vena cava: Azygos vein filter placement and retrieval for pulmonary embolism

The azygos vein serves as an important channel connecting the superior and inferior vena cava (IVC). When venous return through the IVC is obstructed, this pathway becomes a crucial collateral circulation route. This article reports a case of a 39-year-old woman with complete absence of the IVC accompanied by pulmonary embolism (PE). A retrievable vena cava filter was placed in the azygos vein to prevent life-threatening PE, which was successfully retrieved 1 month postoperatively.