Acquired-B phenomenon in a neonate presenting with necrotizing enterocolitis.

OBJECTIVE: We are reporting a case of acquired B phenomenon in a 14 days old pre-term baby presenting with necrotizing enterocolitis (NEC) where it was detected as an ABO discrepancy.

METHOD: The forward and reverse grouping was done using tube technique as well as column agglutination technique (ABD card and LISS Coombs AHG gel cards, Biorad, Switzerland). The direct antiglobulin test (DAT) was also done on gel card. Further work up was done using acidified (0.1 N HCl) anti-B (pH 6-6.5) polyclonal anti-B (from group A donors) for resolution of ABO discrepancy.

RESULTS: The forward grouping was AB RhD positive with a 'mixed-field' agglutination with anti-B. The reverse grouping using pooled A cells, B cells and O cells gave 'negative' result with both the techniques. Anti-A1 gave 2+ agglutination, anti-H gave 1+ agglutination and autologous control was negative. The DAT was also negative. The patient's previous group on day 1 of life was A RhD positive and had received 1 PRBC (pedibag) transfusion. As the patient's blood culture was positive for Klebsiella pneumoniae, it could have contributed to 'acquired-B' phenomenon. Acidified (0.1 N HCl) anti-B (pH 6-6.5) and polyclonal anti-B yielded no agglutination with patient red cells. The patient was kept on antibiotics subsequently and the blood group after 3 weeks was found to be A RhD positive.

CONCLUSION: This case of 'acquired-B' phenomenon in a neonate with NEC emphasizes the relevance of clinical findings as a guide to resolve blood group discrepancy and deciding further transfusion strategy.