Coagulation Hemostasis: Modern View, Pathology, Diagnostics

Relevance . The hemostasis system is a complex multi-level mechanism that, on the one hand, prevents blood loss when a vessel is damaged, and on the other hand, maintains the blood in a liquid state, preventing excessive thrombi formation. It is implemented with the participation of blood cells, endothelial cells and other cells, as well as several sequentially and mutually activated enzyme systems. There are two types of hemostasis: primary and secondary. As a result of activation of primary hemostasis, a platelet thrombus is formed, secondary hemostasis results in the formation of a fibrin clot. Hemostasis disorders lead to either bleeding or thrombosis, which is one of the most important causes of mortality and morbidity in the world. Aim . To consider modern concepts of the mechanisms of fibrin clot formation in norm and pathology, to provide screening tests for evaluation the pathology of coagulation hemostasis. Results . The review examines the sequence of activation of coagulation hemostasis factors from the standpoint of cellular theory. A description and characteristics of most of the participants in the coagulation hemostasis process are separately provided. The most common causes, mechanisms and manifestations of hypo- and hypercoagulation are described. At the end, the most common screening tests for analyzing the state of coagulation hemostasis are described. Conclusion . According to the cellular model, hemostasis occurs in four overlapping phases (initiation, amplification, propagation, and termination) and occurs on different cell surfaces. Specifically, coagulation is initiated in cells expressing tissue factor, amplifies and propagates on the phospholipid surface of fully activated platelets. Hemostasis involves complex biochemical mechanisms and interactions between the vascular endothelium, coagulation factors, and cellular (mainly platelets) blood components.