Blood clots form when blood thickens, forming a semisolid mass. They normally only form if a blood vessel is injured, such as if there is a cut to the skin, and bleeding starts. The blood thickens and forms a clot at the site of the cut to stop the bleeding.
If a blood clot blocks blood flow to the heart, it can lead to a heart attack. If it occurs in an artery to the brain, it can cause a stroke. If it occurs in arteries in the limbs, it can lead to peripheral artery disease.
