Bleeding / Clotting Disorders

Blood clotting, or blood coagulation, is a complex process involving platelets, coagulation factors present in the blood and blood vessels. When bleeding occurs, the injured blood vessel responds by forming a platelet plug. If a large vessel is cut, it contracts (narrows) to limit bleeding, while the platelets rush to the site to form a plug. After this initial response, coagulation begins as a number of inactive factors in the plasma, called coagulation factors, are activated and form fibrin. Fibrin is a strong protein that actually becomes part of the clot, which is the barrier to bleeding.

Abnormalities in platelets, the coagulation factors that regulate fibrin formation, or defects in the blood vessels themselves, can lead to excessive bleeding. Similarly, excess clotting can cause problems by obstructing veins and arteries (thrombosis).