from Section VI - Hemostatic disorders
Published online by Cambridge University Press: 05 February 2013
Introduction
Bleeding symptoms in the neonatal period usually present a diagnostic and therapeutic challenge for treating physicians. Bleeding disorders may be due to either congenital or acquired coagulation disorders, and may be related to mortality or long-term morbidity when not appropriately and timely diagnosed. While severe congenital coagulation defects usually present in the first hours to days of life with distinct symptoms in otherwise well newborns, acquired coagulation disorders usually present in sick newborns with a variety of presentations and distinct etiologies that differ from older children and adults. In newborns, the diagnosis of coagulation abnormalities based upon plasma concentrations of components of the hemostatic system requires age-appropriate reference ranges because plasma concentrations of several procoagulant and inhibitor proteins are physiologically decreased at birth. The aim of this chapter is to discuss clinical presentation, diagnosis, and management of the most common congenital and acquired bleeding disorders in newborns, excluding platelet disorders.
General information
Developmental hemostasis
Components of the hemostatic system are already synthesized by the fetus starting at 10 weeks’ gestational age. At birth, all factors of the coagulation and fibrinolytic system are present and measurable. However, the concentration of several factors differs significantly from older children and adults. In the coagulation system, plasma concentrations of the vitamin K-dependent factors (F), contact factors, and the capacity to generate thrombin are decreased in newborns as compared to adults, while other factors such as fibrinogen, FV, FVIII, and FXIII are similar or increased at birth (1–3). Plasma concentrations of the inhibitors antithrombin, heparin cofactor II, protein C, and protein S are decreased at birth up to 50% of older children and adult values. By contrast, the plasma concentration of α2-macroglobulin in newborns is increased approximately twice compared with adult values.
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