Advantages of larger volume, less frequent intrauterine red blood cell transfusions for maternal red cell alloimmunization.

Larger volume intravascular transfusions to manage severe maternal red cell alloimmunization in pregnancy may prolong the interval between procedures without increasing maternal, fetal, or neonatal complications. A retrospective cohort study compared the management and outcome of 19 patients with severe red cell alloimmunization managed at two facilities with different intravascular transfusion protocols. The volume of blood transfused, pre- and post-transfusion fetal hematocrit, and interval (days) between intravascular transfusions were compared. The respective maternal, fetal, and neonatal results were compared. The red blood cell volume transfused per procedure and the post- but not pre-transfusion fetal hematocrits were higher at New York Hospital than at Westchester County Medical Center. The interval between transfusions at New York Hospital (25.2 +/- 8.65 days) was longer than at Westchester County Medical Center (13.5 +/- 6.0 days, p < 0.0001). Although larger volume transfusion was occasionally associated with transient fetal bradycardia, all red blood cell transfusions were completed without complication. The adverse outcomes, complication rates, and neonatal outcomes were otherwise similar in both management protocols. It is possible to significantly increase the interval between intravascular transfusions with larger transfusion volumes for the management of severe maternal red cell alloimmunization without undue risk. The overall risk for the fetus and mother may be reduced by performing fewer transfusions and avoiding additional blood product exposures.