ABSTRACT
INTRODUCTION Humans have evolved an intricate hemostatic system that is designed to maintain blood in a fluid state under physiologic conditions but is primed to react to vascular injury in an explosive manner in order to stem blood loss by sealing the defect in the vessel wall. Hemostasis is a normal process that leads to cessation of blood flow from a damaged vessel. Thrombosis, however, is a pathological process, which may occur if the hemostatic stimulus is unregulated, either because the capacity of the inhibitory pathways is impaired or (more commonly) because the capacity of the natural anticoagulant mechanism is overwhelmed by the intensity of the procoagulant stimulus. Thrombosis may be regarded as an ‘accident of nature’ that has not had time to adapt through the lengthy process of evolution to the advances of modern medicine, which allow patients to survive the hemostatic challenge of major surgery and trauma but leave them vulnerable to thrombosis.
