Insights into neonatal thrombosis.

Thrombosis in neonates is gaining increased awareness recently, due to improved diagnostic methods and improved survival of young and sick newborns. This review will address the concept and manifestations of developmental hemostasis with respect to the pathogenesis of thrombosis in this unique age group. Hemostasis is a dynamic process that starts in utero. The coagulation system evolves with age, as evidenced by marked physiological differences in the concentration of the majority of hemostatic proteins in early life compared to adulthood. Overall, increased activity of von Willebrand factor and low levels of coagulation inhibitors promote thrombosis; these counterbalance the delicate, immature and "bleeding prone" hemostatic system. Neonates, especially the sickest preterm ones, are extremely susceptible to thrombotic complications. Thrombosis in neonates will be reviewed, with special focus on perinatal arterial ischemic stroke (PAS). The role of thrombophilia in the pathogenesis of perinatal thrombosis will be discussed and authors will present a meta-analysis of neonatal thrombosis studies regarding thrombophilic risk factors for PAS. As thrombosis presentation, risk and outcomes among neonates may differ from those of older infants and children, treatment options will be briefly reviewed.