The left subclavian vein plays a key role in the absorption of lipids, by allowing products that have been carried by lymph in the thoracic duct to enter the bloodstream.

It carries lymph (water and solutes) from the lymphatic system, as well as chylomicrons or chyle, formed in the intestines from dietary fat and lipids, allowing these to enter the bloodstream; the products of fats and lipids can then be carried by the bloodstream to the hepatic portal vein, and then finally to the liver.

Consequently, the left subclavian vein plays a key role in the absorption of these fats and lipids.

[4][5] It is less commonly used than other approaches, such as the right internal jugular vein, due to the risk of pneumothorax, haemothorax, and puncture of the accompanying subclavian artery.

[7] The cause of the thoracic outlet syndrome, whether a thrombus or external pressure, must be removed immediately.