Red cell alloimmunization among antenatal women attending a tertiary care hospital in south India

BACKGROUND & OBJECTIVES: Detection of maternal alloimmunization against red cell antigens is vital in the management of haemolytic disease of the foetus and newborn (HDFN). This study was conducted to measure the presence of allosensitization to blood group antibodies in the antenatal women attending a tertiary care hospital and to observe the proportion of minor blood group antibodies to assess the benefit of screening for the same. METHODS: All antenatal women registered in the hospital between January 2008 and January 2009, were screened for irregular antibodies using a commercial 3-cell antibody screening panel. Antibody identification was performed on samples found positive using a commercial 11 cell-panel. RESULTS: Screening was performed on 5347 women, 339 (6.34%) of whom were Rh negative. Allosensitization was found in 79 women (1.48%; confidence interval 1.17 -1.84). In 29 of these 79 (37%) women the allo-antibodies could not be identified. In the remaining 50 women, 54 antibodies were characterized. A total of 40 clinically significant antibody specificities were identified among 36 women, of whom four were Rh(D) positive. Allosensitization with clinically significant antibodies was found in 9.43 per cent (confidence interval 6.55-13.06) Rh(D) negative and in 0.08 per cent (confidence interval.02-0.2) Rh(D) positive women. Anti D was the most frequent antibody found in 8.85 per cent Rh(D) negative women. The remaining clinically significant antibodies identified included anti-C, c, E, Jk(a), Jk(b), M and S. In Rh(D) negative women, anti-D and antibodies of the Rh system contributed 83.3 and 94.4 per cent of clinically significant antibodies. However, in Rh(D) positive women, non-Rh antibodies comprised three out of four clinically significant antibodies. INTERPRETATION & CONCLUSIONS: The presence of alloimmunization in our study corroborated with data reported from India. The most frequent antibody was anti-D. However, a significant fraction was non-D. Alloimmunization among Rh(D) positive women though low as compared to Rh(D) negative women, included clinically significant antibodies, and most of these were non Rh.