Hemiazygos vein

Looks like

A vein running up the left side of the lower thoracic spine, behind the aorta, then crossing to the right to join the azygos.

What it does

Drains the lower left chest wall and part of the oesophagus.

Keeping it well

Provides a detour for blood if the inferior vena cava is blocked; it then widens and shows on scans.

Related conditions

• Chronic venous insufficiency
• Clotting disorders (thrombophilia & APS)
• Deep vein thrombosis
• Varicose veins