Relationship between maternal antibody type and antenatal course following intrauterine transfusion for red cell alloimmunisation.

OBJECTIVE To determine the antenatal course of severe red cell alloimmunisation in pregnancies requiring intrauterine fetal transfusion. STUDY DESIGN A retrospective cohort study over 16 years in a single national quaternary fetal medicine centre. From 1996 to 2011, 242 red cell intrauterine transfusions (IUT) were performed in 102 alloimmunised pregnancies. Antibody type was categorized into Rh(D) and non-Rh(D) (including Rh(c), Kell and Rh(E)). Women with Rh(D) antibodies were further stratified into those with and without additional red cell antibodies. Data were compared using the Mann-Whitney U and Fisher's exact tests. Two-tailed P values at the 5% level were considered significant. RESULTS Comparing Rh(D) and non-Rh(D) pregnancies, there were no differences in either gestational age or fetal haemoglobin at first IUT, number of transfusions required, gestation at delivery, caesarean delivery rates or perinatal losses. In women sensitized to Rh(D), the presence of additional antibodies did not influence the degree of fetal anaemia or the first transfusion-delivery interval, although rates of fetal hydrops were higher in the presence of multiple antibodies. The "procedure-related" loss rate was 1.7% per procedure in our institution. CONCLUSION Antibody status does not appear to influence clinical outcomes following fetal transfusion for alloimmunisation.