Anticoagulation is the term used to describe the process which makes a patient's blood less likely to clot. Under normal circumstances, if blood is allowed to stand for a short period of time, it will form a clot.
Blood clotting is a normal body process which protects the body from serious damage.
It helps to assure that when the body is injured, any resulting bleeding will be minimized as a clot forms at the site of the broken blood vessel. In some cases, it is medically necessary to reduce the chance of clot formation. This is true for patients who have mechanical heart valves. These patients' blood will be thinned to lesson the chance of clot formation due simply to the existence of an artificial valve. Other patients who are often anticoagulated are those who have an abnormal heart rhythm, such as atrial fibrillation, or who are experiencing significant degrees of heart failure , and are therefore at risk of developing a clot due to the less effective pumping action of the heart.