1. Slower blood flow in the vein (venous stasis) due to immobility
It may happen when someone:
- undergoes a surgery that is performed under general anaesthesia
- has a fracture
- gets admitted to an intensive care unit
- suffers a major stroke
- has a long haul travel
2. Injury to the lining of the vein (endothelial injury)
Causes of endothelial injury include:
- Previous DVT
- Inflammation of the vessel wall (vasculitis)
- Intravascular catheter (for administration of drugs)
- Injection of illicit drug by drug users
They are conditions that increase the risk of blood clot. Some examples include nephrotic syndrome, anti-phospholipid syndrome and protein C deficiency.
Other risk factors of DVT include cancer, pregnancy, obesity, use of oral contraceptive pills or hormonal replacement therapy.