“Thrombosis” means clotting; a “thrombus” is a clot. They can rarely develop in the heart, but the vast majority occur in veins. That’s because blood in veins ekes along slowly as it returns to the heart, whereas blood in the arteries gets pumped too vigorously to stagnate and clot. If this is confusing, see Blood Vessels. Synonyms for venous thrombosis include “thrombophlebitis,” and “venous thromboembolism”
Venous thrombosis can be superficial or deep. Superficial clots tend to hurt more, and the veins may look inflamed. But it’s in the deep larger veins where bigger clots have more potential to break loose and flow up into the lungs, causing a fatal Pulmonary Embolism.
Deep Venous Thrombosis (DVT) usually occurs in the legs or pelvis, where blood can pool. It’s possible, but much less likely, to occur in the arms. Other parts of the body that can rarely be subject to clots include the liver (Portal Vein Thrombosis), veins from the intestines (Mesenteric Venous Thrombosis), the retina of the eye, and Cavernous Venous Thrombosis in the large vein from the brain.
Thrombosis can be caused by a variety of conditions, which include:
- Immobility in the legs (from long leg casts, or general anesthesia);
- Clotting tendencies related to heredity, pregnancy, and active cancer;
- In the abdomen, various inflammatory diseases, surgery, or trauma;
- In the eye, a variety of risk factors like old age, hypertension, glaucoma, smoking, and more
- In the brain, which is rare, it mainly occurs in persons with tendencies to clot as noted above.
Treatment for all forms of thrombosis involves anticoagulants (“blood thinners”), which prevent further clot formation, and allows the body to dissolve what’s already there. Only in the most extreme of circumstances would specialists attempt to remove the clot. Without treatment, there’s risk of permanent damage to the affected organ.