Thrombosis is a disease in which a blood clot (thrombus) forms in the veins, which can partially or completely block the blood flow. The formation of blood clots is caused by a coagulation disorder.
Blood clots can form in different areas of the circulatory system, but are most often formed in the deep veins, typically in the lower limbs, as blood circulation can slow down more easily here. A blood clot can also form in the upper veins, but this is mostly harmless and easy to treat.
If the resulting blood clot is loosely attached to the vessel wall, it can easily come off and the detached blood clot (embolus) will start to drift with the bloodstream. A detached blood clot causes a serious problem when it arrives at a narrower blood vessel section and becomes wedged in and blocks the blood flow. This is when an embolism develops. Blood clots detached from the veins of the legs usually pass through the heart and block one or more arteries in the lungs, causing pulmonary embolism.
It is important to take the symptoms of thrombosis seriously so that major trouble can be prevented and avoided. The most common symptoms are a swollen, red, touch-sensitive, warm limb, which most often occurs around the foot, ankle, or thigh. Swelling is caused by fluid build-up (oedema), which can lead to ulcers later if left untreated. If you experience symptoms, visit an emergency room as soon as possible.