Which structure may be involved if there is an obstruction leading to decreased venous return from the renal veins?

The inferior vena cava plays a crucial role in the venous return system, particularly in draining blood from the lower half of the body, including the renal veins, which carry deoxygenated blood away from the kidneys. If there is an obstruction in the inferior vena cava, it can hinder the flow of blood returning from the renal veins, leading to decreased venous return from the kidneys.

This situation can result from various conditions, such as thrombosis, external compression, or tumors that may physically block the inferior vena cava. When blood flow through this major vein is compromised, the pressure in the renal veins can increase, impacting kidney function and overall circulation.

The other structures mentioned, such as the common iliac veins, femoral veins, and deep femoral veins, while they do have roles in venous circulation, are not directly responsible for the drainage route of the renal veins into the systemic circulation. Therefore, an obstruction in these veins would not primarily lead to decreased venous return from the renal veins in the same way that an obstruction in the inferior vena cava would.