Significance of serological monitoring in a Bombay Rh (D) negative phenotype pregnant woman: a case report.

A 32 year old Indian female was referred to our hospital at 32 weeks of gestation because of difficulty in blood group determination and further antenatal care. The results of cell and serum grouping of her blood sample were suggestive of Bombay (O(h)) Rh (D) negative phenotype. An indirect antiglobulin test (IAT) using a pool of red cells from two Bombay Rh (D) positive blood donors gave negative result using the tube as well as the gel technique (LISS-Coombs Card, BioRad, Switzerland), thus ruling out anti-D antibody in her serum. The anti-H titer was 16 (tube technique) and with dithiothreitol (DTT) treated patient's serum the antibody screening was negative suggestive of IgM type of anti-H antibodies. Within the patient's family, only one member (younger sister) was of O(h) phenotype and also was Rh (D) negative. The baby was born vaginally at 38+6 weeks of gestation and was non-hydropic with a packed cell volume (PCV) of 55%. The baby's blood group was AB Rh (D) negative and the cord blood direct antiglobulin test (DAT) was negative. Thus, a careful serological testing of O(h) phenotype antenatal women especially with Rh (D) negative phenotype is of utmost importance in determining the isoimmunization status.