Normal coagulation findings, thrombocytopenia, and peripheral hemoconcentration in neonatal polycythemia.

The criteria used for partial plasma exchange transfusion in 32 of 42 polycythemic newborn infants with capillary hematocrits greater than or equal to 70% were a venous hematocrit greater than 65% and two or more clinical "symptoms," or a venous hematocrit greater than or equal to 70%. Coagulation tests performed on 20 infants before and after the partial plasma exchange transfusion were normal for age. Low platelet counts found in six of the 32 patients were associated with venous hematocrits of greater than or equal to 70%. In three patients the platelet counts (less than 100,000/microliters) increased to greater than or equal to 130,000/microliters after three days. In 20 of 32 infants in whom partial plasma exchange transfusions were performed, peripheral venous hematocrits prior to the exchange were 8.5% higher than umbilical venous hematocrits. Following treatment the venous hematocrits (umbilical and peripheral) did not show a statistically significant difference. Thus, the study revealed coagulation findings normal for age, thrombocytopenia in 20% of polycythemic infants, hemoconcentration, and a sluggish peripheral venous circulation.