Introduction to Coagulation System

ABSTRACT

Coagulation involves the regulated sequence of proteolytic activation of a series of proteins to achieve appropriate and timely hemostasis in an injured vessel. In the non-pathological state, the inciting event involves exposure of circulating factor VIIa to extravascularly expressed tissue factor, which brings into motion the series of steps which results in cell based model of coagulation. In the new concepts of coagulation system, initiation, amplification and propagation steps are involved to converse of fibrinogen to fibrin. The precisely synchronized cascade of events is counter-balanced by a system of anticoagulant mechanisms. Developmental hemostasis refers to the age-related changes in the coagulation system that are most marked during neonate and childhood. An understanding of these changes in crucial to the accurate diagnosis of hemostatic abnormalities in neonate and children. This review aims to elucidate the main events within the coagulation cascade as it is currently understood to operate in vivo, and also a short review of the anticoagulants as they relate to this model. Also this paper describes the common pitfalls observed in the clinical data related to the coagulation system in neonate to children.