The effect of the source of transfused blood on the rate of consumption of transfused red blood cells in pregnancies affected by red blood cell alloimmunization.

Objective: Our purpose was to compare the rate of consumption of maternally donated red blood cells with the rate of red blood cells from volunteers in fetuses affected by red blood cell alloimmunization.

Study Design: The rate of hemoglobin decline was calculated in 293 fetal transfusions in 52 pregnancies, in 43 patients affected by red blood cell alloimmunization from 1987 to 1996. Fifty-eight transfusions were excluded from analysis. Hemoglobin decline was stratified by gestational age. The rates of consumption were compared with use of unpaired t tests.

Results: The rates of hemoglobin decline (in grams per deciliter per day) were 18 to 24 weeks, 0.47 volunteer and 0.38 maternal (p = 0.174); 25 to 28 weeks 0.41 volunteer, 0.34 maternal (p = 0.46); 29 to 32 weeks, 0.35 volunteer, 0.33 maternal; > or = 33 weeks, 0.37 volunteer, 0.25 maternal, p = 0.048). Hemoglobin decline was less for the maternal donation group than for the volunteer donation group throughout gestation, becoming significant only in fetuses at > or = 33 weeks.

Conclusion: In the red blood cell-alloimmunized fetus, there is less consumption of maternal than of volunteer red blood cells. This difference reaches a statistical significance only in late gestation.