[ADP and collagen-induced thrombocyte aggregation in umbilical cord vein blood]

ADP and collagen induced platelet aggregation were determined in 34 newborns immediately after birth. Blood was drawn from the pulsating not clamped umbilical vein. Parameters of aggregation were correlated to pH values of umbilical artery and vein, Apgar score and to the duration of the first and second stage of labor. No significant correlations were found between parameters of labor and platelet aggregation. It is demonstrated, however, that a decrease of the pH values in the umbilical artery and vein is well correlated with an increase of the main parameters of platelet aggregation. Changes of disaggregation of platelets were only moderate, they showed a tendency to decrease with falling pH values. Altogether there is an increase of platelet aggregability if pH values go down. The results emphasize that the changes of platelet function described should be regarded in the concept of therapy of newborns with severe acidosis or shock as they may accentuate preexisting hypercoagulability.