It depends. It depends on many factors- i.e. How extensive the blood clots are; is this the first event? What is the cause- related to malignancy, post-trauma, related to paraplegia-whether the cause is on going? Whether you have significant hypercoagulable problems like protein c, s deficiency etc. There are many things that have to be calculated to figure out the length of therapy.
Time. 3-6 months.