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Changes in hemorheology with fetal intravascular transfusion
R Welch1, M W Rampling, A Anwar
1Fetal Medicine Unit, Queen Charlotte's and Chelsea Hospital, London, United Kingdom.
Objective:
Our aim was to determine the changes in fetal hemorheologic parameters caused by fetal intravascular transfusion for alloimmune anemia.
Study Design:
Fetal blood samples were collected before and after 95 fetal transfusions in 31 women. Fetal hematocrit, whole-blood viscosity at a variety of shear rates, plasma viscosity, fetal fibrinogen, and fetal plasma proteins were measured.
Results:
Fetal whole-blood viscosity increased, sometimes massively, with transfusion. The rise in viscosity was principally dependent on the rise in hematocrit, with a linear rise in hematocrit producing a linear rise in the logarithm of whole-blood viscosity, but was also affected by the amount of adult plasma proteins present in the donor blood.
Conclusions:
Rises in fetal whole-blood viscosity during transfusion can be minimized by using donor blood that has been serum depleted to a high hematocrit (> 90%) and by restricting the end hematocrit to 50% to 55%.