At thrombosis, a vein or varicose vein is blocked by a blood clot. This can occur in both the deep and superficial leg vein system and lead to leg swelling, overheating, a feeling of tightness and pain.

Causes often include immobility, long travel, unusual physical exertion, injury, surgery, infection, and many other less common causes.

Therapy is individualized depending on the extent and location of the thrombosis. The main goal is to prevent pulmonary embolism and permanent damage to the vascular system.