Venous thrombosis is an abnormality in the blood clotting process in a vein. Depending on the venous system involved, the venous thrombosis may be deep or superficial and Usually involves the lower limbs.

We talk about thrombosis when there is a thrombus, or a blood clot. Coagulation is a physiological and essential phenomenon for our body. When, however, a clot is created at the wrong time and place a thrombus sets in, which can have consequences.

Dr. Corrado Lodigiani, Head of the Humanitas Center for Thrombosis and Hemorrhagic Diseases, breaks down the risk factors and tells us what causes venous thrombosis in an interview with Corriere della Sera.


Why do blood clots form?

“The clot is formed because the blood coagulates in an intact vein, one that is not injured. You can solve the problem yourself through the fibrinolysis process, a physiological mechanism to thin the thrombus almost completely. However, to make use of this process, the clot should be small and peripheral, for example, in the muscle tissue.

The clot may also be formed secondary to other pathologies, such as a tumor or infection, or after surgery. When someone undergoes surgery, the blood circulation is reactivated and if the coagulation stimulus to stop the bleeding prevails, it can produce a clot. Therefore, it is good to submit patients at greater risk of thromboembolic prophylaxis to drugs capable of restoring balance, such as anticoagulants,” says Dr. Lodigiani.


What are the risk factors?

“In addition to what we are already familiar with and the presence of genetic clotting problems (thrombophilia) there are several other risk factors. These include taking medications that alter the prothrombotic balance of the coagulation system, such as birth control pills or hormone replacement therapy. Pregnancy also increases the chances of developing thrombosis. This pathological condition is frequent in case of obesity, venous insufficiency with varicose veins or if you are very sedentary and suffer from diabetes or severe dyslipidemia. The latter has emerged only in recent years”, says Dr Lodigiani.


Precautions on long-haul flights

Long-haul flights may favor the onset of thrombosis. Thrombosis should not be confused with edema, or swelling of ankles and calves.

Dr. Lodigiani concludes: “Sometimes swelling may simply be due to stagnation and not a sign of deep venous thrombosis. The risk of edema, as well as the risk of deep venous thrombosis can be avoided using socks and exercising while sitting down with your feet and ankles, and getting up once in a while”.