Deep vein thrombosis refers to the clotting of the blood that develops in the vein of the body that is deep, which usually involves the veins in the leg. Such a vein is large and passes through the calf muscles and the muscles of the thigh. In the veins, the blood clots that have developed are called venous thrombosis. There are cases wherein there is no specific cause for the development of deep vein thrombosis.

However, under some circumstances, it has been observed that the condition develops potentially due to the following factors:

1. Inactive lifestyle
When a person is inactive, their blood tends to gather mostly in the lower parts of the body. This is not a worrisome situation because when a person starts to move, the blood starts circulating all around the body evenly. But if a person is not able to move for a long time, for instance, after an operation, due to an injury or an illness, or during a long journey, the blood flow will become slow to quite an extent. When the blood flows slowly, the chances of developing a blood clot may increase.

2. Health complications
If a person is suffering from other health-related complications, the risk of developing blood clots increases. The reason behind this is that deep vein thrombosis can develop when a person is inactive or unwell or when a person is not very active. The risk of developing deep vein thrombosis is identified on the kind of treatment the person is receiving. In the following cases the risk of developing DVT increases:

• If a person is having an operation of the abdomen, hip, or leg that may take more than sixty or ninety minutes
• If a person is having an operation for a condition of the abdomen like appendicitis or any inflammation
• If a person is confined to the bed and is unable to walk or if a person is spending a lot of time in a chair or a bed for at least three days.

3. Following surgery
The risk of developing deep vein thrombosis increases if the person is very inactive due to an operation or an injury and also suffers from other risk factors associated with deep vein thrombosis. When a person is admitted to a hospital, the person needs to be assessed well to check for any developing blood clots. If required, preventive treatments should also be given to the patient.

4. Damage to blood vessels
If there is damage to the wall of a blood vessel, it may get blocked or narrowed, which can lead to the development of blood clots. The damage can occur to the blood vessels in an injury like that of a broken bone or severe damage caused to the muscle. There are times wherein the damage caused to the blood vessel could be during surgery. Under such circumstances, blood clots can develop during an operation in the lower part of the body. Damage to the blood vessels can also occur during a certain type of medication like chemotherapy as well as in conditions like varicose veins and vasculitis.