Changes in hemorheology with fetal intravascular transfusion

Fetal transfusions may be most effective if donor blood with a very high hematocrit is used and the fetal hematocrit is elevated to approximately 55%. Transfusing blood to a fetus through umbilical cord vessels is used to treat severe anemia in the fetus. Hematocrit is the ratio of packed red blood cells to the total volume of blood. Researchers studied samples of fetal blood before and after 95 fetal transfusions in 31 patients. The blood samples were analyzed for viscosity and levels of hematocrit, fibrinogen and proteins. Viscosity of fetal blood increased significantly after transfusion. The rise in viscosity was associated with a rise in fetal hematocrit and also with the amount of proteins in the plasma of donor blood. There was no significant change in fibrinogen levels. The transfusion of adult plasma proteins should be reduced as much as possible by cleansing donor blood of plasma and using blood with a hematocrit close to 100%.