Evaluation of primary hemostasis in neonates with a new in vitro platelet function analyzer.

With the use of the PFA-100 platelet function analyzer to evaluate primary hemostasis in whole blood, measured as closure time (CT), neonates had shorter CTs than members of an adult control group. Multivariate analysis of measures that contribute to primary hemostasis showed that higher hematocrits and increased ristocetin cofactor activity were the best correlates for CTs of cord blood. These 2 factors may also enhance primary hemostasis in vivo and compensate for the impaired platelet function of the newborn.