Bombay phenotype (O_h) and high‐titer anti‐H in pregnancy: two case reports and a review of the literature

Abstract

BACKGROUND Antenatal cases of Bombay‐phenotype (Oh) individuals and hemolytic disease of the fetus and newborn (HDFN) are not well described in the literature. We present two case reports of high‐titer anti‐H in pregnant Oh individuals and their serologic investigation, clinical management, and subsequent outcomes. We describe current published cases detailing pregnancy in Oh individuals, to add to the evidence base for clinical decision making and management of pregnancy. STUDY DESIGN AND METHODS We describe two case reports of high‐titer anti‐H in pregnancy in Oh individuals. We summarize published cases to date, to inform clinical decision making and antenatal management in individuals with the Bombay phenotype. RESULTS Of the case reports described, neither were affected by HDFN due to anti‐H. Antibody titers were high in both cases (immunoglobulin G titer scores, 512 and 4000, respectively) and would be expected to cause some degree of HDFN, a surprising finding. Regular mean cerebral artery Doppler ultrasound was normal. Patient blood management (PBM) techniques ensured that the patient's hemoglobin (Hb) levels were monitored and maintained. Transfusion intervention was not required, with minimal blood loss recorded at birth in both cases. CONCLUSION High‐titer anti‐H in Oh pregnancies may, in rare cases, cause HDFN, but evidence suggests that this may not be the case in all pregnancies. We recommend a multidisciplinary approach, with prompt referral to a fetomaternal medicine unit, combined with PBM strategies, and a planned delivery with the provision of rare‐phenotype units (if available and if indicated) on standby.

The Bombay Blood Group: How Rare is It? A Case Report and a Review of the Literature

“…The Bombay blood group is a rare type of blood group with the possibilities of causing haemolytic disease of the foetus and newborn and blood transfusion reactions, although case reports are quite conflicting regarding this, and also because there are only a few published case reports in the literature [7,11]. With only 9 case reports till date, this further buttresses the rarity of this condition [3,7,11,12].…”

“…The H antigen is discrete, and it is usually the precursor of specific molecules known as the A and B molecules or antigens, which are formed by the addition of individual sugar molecules known as immunodominant terminal monosaccharides N-acetylgalactosamine and galactose [10].…”

“…Blood group A depicts individuals with the presence of the A antigen and B antibodies; group B represents individuals with the presence of the B antigen and the A antibody; blood group AB occurs in individuals who possess the AB antigen with no corresponding antibody; and blood group O individuals have the A and B antibodies present on the surface of their red blood cells (RBCs) but without any corresponding antigen [3]. Although individuals with blood group O have the A and B antibodies present on their RBC surfaces, they lack the H antibody (since they harbour the H antigen), while individuals with Bombay blood group have A and B antibodies as well as H antibodies [1,3,10]. The ABO blood group and the Bombay blood group characteristics are depicted in Table 1.…”

“…The clinical relevance of the Bombay or the OH phenotype lies in the ability to cause haemolytic disease of the foetus and the newborn (HDFN) with its attendant consequences as the antibodies cross the placenta into the foetal circulation [1,6,7]. It is unclear, but has been noted that the OH phenotype can result in blood transfusion reaction if individuals with the Bombay blood group receive blood from other groups [3,[8][9][10]. It may be very challenging in emergency circumstances where there could be a delay in finding the Bombay blood group phenotype, and in such scenario, it is advised to only administer plasma expanders [3,10].…”

“…It is unclear, but has been noted that the OH phenotype can result in blood transfusion reaction if individuals with the Bombay blood group receive blood from other groups [3,[8][9][10]. It may be very challenging in emergency circumstances where there could be a delay in finding the Bombay blood group phenotype, and in such scenario, it is advised to only administer plasma expanders [3,10].…”