111 - Developmental Hemostasis

Abstract

In the mid-1800s Rudolf Virchow described a triad of factors that contributed to pathologic blood clotting: blood flow, blood vessel wall, and blood composition. The description is still relevant nowadays and, in fact, is just as relevant to the development of bleeding as it is to abnormal clotting. Hemostasis involves complex interactions among the vascular endothelium, cellular elements within blood (particularly the platelets), and plasma proteins in the context of blood flow. Although developmental hemostasis is often discussed purely in terms of changes in plasma proteins, it is important to remember that all of the elements of the Virchow triad change with age. Furthermore, changes in plasma proteins are not restricted to the proteins that constitute the coagulation system but occur throughout the entire plasma proteome. Although hemostasis is a dynamic, evolving process that is age dependent and begins in utero, there is arguably no greater time of change in the hemostatic system than around the time of birth. Although evolving, the hemostatic system in healthy fetuses and infants must be considered physiologic. The evaluation of newborn infants for hemorrhagic or thrombotic complications presents unique problems that are not encountered in older children and adults. An understanding of developmental hemostasis in the broadest sense optimizes the prevention, diagnosis, and treatment of hemostatic problems during infancy and undoubtedly provides new insights into the pathophysiology of hemorrhagic and thrombotic complications for all ages.