If the coagulation system is out of balance, this results in either an increased willingness to bleed or a tendency towards increased willingness to coagulate, thromboses and embolisms.
Blood coagulation is a complex process that occurs like a chain reaction involving various coagulation factors.
The normal blood coagulation coagulation factors are blood proteins which, when activated accordingly, change from a liquid to a solid state of aggregation, coagulate and solidify in a similar way to egg white when heated appropriately. This so-called “exogenous” coagulation is triggered by platelets, which accumulate in large numbers at the site of vascular injuries and secrete messenger substances that activate the coagulation factors. The result of this interaction is a blood clot – also called thrombus – that closes the injured blood vessels. Thrombi formed in this way are rich in thrombocytes and are called “white” thrombi.
The formation of blood clots can also take place without activation via the platelets, for example if the blood contains too high a concentration of blood clotting factors. In this case, the blood can stall without damaging vessels or tissue.
Pathological blood clots can be located either in the veins, in the arteries or in the heart cavities, or thrombosis in the narrow sense is the formation of clots in the venous system or inside the heart. This is mainly due to an imbalance in plasma coagulation or platelet function disorders as well as physical reasons – an excessively slow flow rate of the blood. The increased tendency to thrombosis can be either congenital or acquired.