Neonatal platelet physiology and pathophysiology

Platelets contribute to primary haemostatic events and are closely linked to plasmatic coagulation. Their function is highly dependent not only on their number but also on their integral physiology. In comparison with adults or children, the haemostasis of newborn infants, although physiological, is characterized by a reduced functional reserve capacity leading to the rapid occurrence of bleeding disorders especially in the presence of additional risk factors such as prematurity, asphyxia, or infection. Morphological and biochemical differences reflect an immature cellular stage which results in platelet hyporeactivity and contributes to the reduced capacity of the neonatal haemostatic system. Additionally acquired and inherited platelet disorders markedly affect platelet function. Hence assessment of neonatal platelet physiology may supply important information, however, no adequate screening tests are currently available, and technical difficulties of blood sampling limit the value of laboratory testing. Evaluation of the neonatal platelet function is highly dependent on individual laboratory results and it is advisable to perform complex diagnostic procedures with the collaboration of specialists experienced in neonatal haematology. With the advent of new technology such as platelet flow cytometry more adequate tools are available, although still reserved for specialized laboratories, thus awaiting their clinical significance. The role of maternal influences on neonatal platelet function must be always considered. Thus, neonatal platelet physiology and pathophysiology is complex and require more studies and experience.