You can get deep vein thrombosis through several different ways.
Some people get deep vein thrombosis because of certain medical conditions that affect how the persons blood clots.
The deep vein thrombosis can also happen if you don't move for a long time, such as after surgery or an accident, or when you're confined to bed.
When your blood clots due to inactivity it can lead to you developing deep vein thrombosis.
If you do get deep vein thrombosis you should see a doctor about it because you could be getting blood clots in your leg that can get more serious and lead to a heart attack, stroke or even death.
Make sure you get up and move around often too because not moving around or sitting too long and not walking or exercising enough can lead to deep vein thrombosis.