Sampling problems are common in the newborn period, and it is particularly important that samples for coagulation testing avoid contamination or activation before analysis. The results of these initial screening tests can then be used to guide the direction of further investigations.
#Dic lab findings full
Initial screening investigations usually comprise a full blood count and a baseline coagulation screen. Finally both maternal and neonatal drugs, particularly with regard to vitamin K metabolism, may be highly relevant at this time. Obstetric complications and problems at delivery can also affect the haemostatic system resulting in coagulation activation and DIC. The presence of a family history of a bleeding disorder or of a previously affected infant can also be an important diagnostic pointer.
Bleeding in an otherwise well neonate is much more suggestive of an inherited coagulation or an immune mediated thrombocytopenia, whereas a sick preterm neonate is more likely to have a consumptive coagulopathy with disseminated intravascular coagulation (DIC). Most important of these is probably the clinical setting in which the bleeding occurs. INVESTIGATION OF THE NEONATE WITH ABNORMAL BLEEDING Clinical considerationsĪ number of clinical considerations are important in the investigation of a neonate with a haemorrhagic problem and a possible underlying coagulopathy. 5 This probably reflects multiple factors including increased concentrations of von Willebrand factor (vWF), the presence of large vWF multimers, and the high neonatal packed cell volume. Despite this, the bleeding time, which can be viewed as an in vivo assessment of the platelet-vessel wall interaction, is shortened in normal healthy neonates. Although neonatal platelet numbers are normal, studies of platelet function suggest that neonatal platelets are hyporeactive compared with adult platelets. Thus the platelet count is within the normal adult range in both term and preterm infants. Platelets are also influenced by age, although qualitatively rather than quantitatively. The haemostatic system matures during the early weeks and months of life, and the concentrations of most haemostatic proteins, both in term and preterm infants, are very close to adult values by 6 months of age. 4ĭespite this apparent functional immaturity, the neonatal haemostatic system seems to result in relatively few clinical bleeding problems for the healthy term infant. 2, 3 Plasminogen is the major protein involved in fibrinolysis, and again this is reduced during the neonatal period, resulting in a relatively hypofibrinolytic state. 2, 3 Similarly, concentrations of the naturally occurring anticoagulants, antithrombin, protein C, and protein S, are low at birth, and, as a consequence, both thrombin generation and thrombin inhibition are reduced in the newborn period.
At birth, concentrations of the vitamin K dependent (FII, FVII, FIX, FX) and contact factors (FXI, FXII) are reduced to about 50% of normal adult values and are further reduced in preterm infants. The haemostatic system is profoundly influenced by age, and the concentrations of many haemostatic proteins are dependent on both the gestational and postnatal age of the infant. 1Īn understanding of the haemostatic system and features unique to the early weeks of life is important when it comes to the investigation of a neonate with a haemorrhagic problem. It is now recognised that the traditional extrinsic pathway, involving tissue factor and factor VIIa, is the major pathway whereby coagulation is initiated, and that thrombin plays a crucial role in both the activation and inhibition of coagulation and also in platelet activation. Our understanding of this process has improved considerably in recent years, and it is now accepted that traditional models of haemostasis do not adequately reflect events in vivo and are an oversimplification of the processes involved.
#Dic lab findings series
Normal haemostasis reflects a highly complex process, which is dependent on a series of interactions occurring between endothelial cells, platelets, and haemostatic proteins.
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