The rare lifeline: struggle and strategy behind O_h (Bombay) blood group transfusions Open Access

O_h (Bombay) phenotype is a rare genetic trait that is characterized by the absence of H antigen on the surface of red blood cells. Thus, ABO genes cannot be expressed as A and/or B antigens. The frequency of prevalence of O_h group in India and Europe are 0.01% and 0.0001%, respectively; with rates as high as 0.01% in parts of Mumbai.¹ Due to the rarity of this blood group, securing compatible blood products during emergencies is extremely challenging. This becomes critical in perioperative complications, during which delays can increase morbidity. This case highlights how timely intervention and coordinated efforts overcame significant challenges in managing postoperative complications in a patient with O_h blood group, despite limited donor availability and logistical constraints.

A 61-year-old woman from Maharashtra, India with stage IVB endometrial cancer, hypertension, and prior left kidney donation presented for debulking surgery in August 2024. As a known O_h⁺ patient, her family history revealed only she and her sister shared this blood group, identified during prior testing. The blood center reconfirmed the patient’s group serologically. Cell typing showed O Rh D positivity, whereas serum grouping reacted strongly (4+) with A, B, and O cells. Anti-H showed no agglutination, confirming O_h phenotype.

In view of the patient’s rare blood group, as well as a hemoglobin (Hb) level of 9.2 g/dL, the physician was advised to initiate IV iron supplementation to optimize Hb because obtaining O_h⁺ blood units is challenging due to their rarity. The blood center was entrusted to arrange 2 units of O_h⁺ packed red blood cell (PRBC) units for anticipated bleed during surgery. Two units were found in 2 different blood centers and were transported under strict cold chain conditions to our center. Because the surgery went without much blood loss (∼400 mL), no intraoperative blood transfusion was required. Postoperatively, on day 1, a unit of blood was transfused because Hb was 6.6 g/dL, and the patient was then discharged on day 2.

Fifteen days after debulking surgery, the patient presented with postoperative surgical site infection. Complete blood count revealed an Hb level of 8.6 g/dL and platelet count 271 × 10⁹/L. She underwent surgical debridement under local anesthesia with vacuum-assisted closure, after which her counts remained stable. The patient was discharged with vacuum-assisted closure in situ and advised close follow-up. Within a week, however, she represented to the emergency department after a fall, reporting generalized weakness and drowsiness. Upon admission, her Hb level was 8.2 g/dL, and platelet count was 342 × 10⁹/L. Evaluation revealed a surgical site infection, with wound swab culture growing Klebsiella pneumoniae and Pseudomonas aeruginosa. Sensitivity testing showed Klebsiella was resistant to all antibiotics except tetracycline, whereas Pseudomonas remained sensitive. The patient was admitted to the intensive care unit, with continuous complete blood count, thromboelastography monitoring, and transfusion support was provided when Hb <7 g/dL, as shown in Figure 1A.

Securing O_h blood group units was highly challenging, hindered by urgent donor identification, nationwide logistical delays, and the patient’s rapidly worsening condition, which intensified both the urgency and complexity of timely transfusion management. To tackle the challenges effectively, a 2-pronged strategy was adopted: (1) explore possibility of autologous blood transfusion; and (2) identify compatible donors either from family members or through the Rare Blood Group Registry.

Because the patient presented as critical postoperatively, autologous whole blood donation was unfeasible. Of all family members tested, only a sibling was identified to have O_h blood group. However, she was ineligible for donation. Hence, assistance for PRBC support was sought from a local nongovernmental organization that works specifically with O_h blood group donors. A few donors donated whole blood; 2 at our center, 4 at nearby centers, transported via cold chain, and 1 from another city, which was transported with nongovernmental organization assistance, ensuring proper cold chain maintenance, which is depicted in Figure 1B. She received a total transfusion of 7 units of O_h⁺ PRBC, 8 random donor platelet and 7 single-donor platelet units of A₂⁺ blood, and 24 fresh frozen plasma and 20 cryoprecipitate units of O⁺ blood group. Despite 20 days of intensive management, the patient ultimately succumbed.

The O_h blood group, first described by Bhende et al² in 1952 in Mumbai (previously Bombay), is a rare autosomal recessive blood type. It was identified when panreactive antibodies in 3 apparent group “O” individuals reacted with all non-O_h red cells. The defect lies in the FUT1 gene, which fails to code for α-2-L-fucosyltransferase, preventing H-antigen formation on red cells; additional FUT2 mutations affect antigen secretion.¹ Individuals produce anti-H antibodies (immunoglobulin M and immunoglobulin G), capable of complement activation, leading to intravascular hemolysis, severe transfusion reactions, and hemolytic disease of fetus/newborn.³ The closely linked RHD and RHCE genes often undergo recombination or mutation, producing Rh variants, although underlying mechanisms remain complex despite advances in genetic testing.^4,5 In routine ABO grouping, individuals with O_h phenotype initially appear as group O. The O_h phenotype becomes apparent during antibody screening and identification tests showing strong pan-agglutination (4+) pattern in all cell panels. Anti-H present in O_h individuals cause strong agglutination/hemolysis with group O red cells.⁶ 

Sathe et al⁷ reported that most cases occurred in Maharashtra, followed by Karnataka, Andhra Pradesh, Goa, and Gujarat. This allowed for multiple donors to be available locally for our case. Balgir⁸ found higher prevalence among certain Orissa tribes, linked to endogamy and consanguinity. Thus, regions with greater consanguineous practices show increased probability for O_h blood group, underscoring the impact of genetic and social factors on its distribution. Cooling et al⁹ showed that A₁ cells express high A and low H antigens, whereas A₂ cells lack A antigen. A₂ platelets, lacking both A and H antigens, likely due to differing glycosyltransferase activity, mimic the O_h phenotype, allowing for successful transfusion of A₂ random donor platelets and single-donor platelets units, as was done in this case.

A 2024 Times of India report¹⁰ estimated ∼450 registered individuals in India with the rare O_h blood group, including nearly 200 in Maharashtra, including ∼140 in Mumbai and nearby suburbs. However, stringent medical screening reduces eligible donors to ∼60 in Mumbai, severely limiting availability during emergencies. This scarcity emphasizes the urgent need for a structured donor network. In response, the Hindustan Times¹¹ reported that Maharashtra State Blood Transfusion Council has initiated a centralized registry of O_h donors by directing all state blood centers to submit detailed donor data. This registry aims to strengthen both intrastate and interstate coordination, enabling faster mobilization of compatible blood units during crisis. At the national level, the Indian Council of Medical Research–National Institute of Immunohematology (ICMR–NIIH) is collaborating with Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh; Medical College Hospital Kolkata, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry; and King Edward Memorial (KEM) Hospital, Mumbai, to establish a nationwide database, enhancing donor identification and improving emergency transfusion outcomes for this rare phenotype. India, having more registered O_h blood group donors than most countries, often supports international requests through intricate logistics. Units have been transported to Bangladesh and Nepal, while 2 Indian donors personally traveled to Vietnam to provide lifesaving donations due to the nation’s prohibition on importing blood products.¹¹ 

Several reports describe strategies for managing patients with the O_h blood group. Van Denakker et al¹² outlined approaches such as intraoperative cell salvage, reserving frozen O_h units sourced from different states, and using HBOC-201 (bovine Hb–based oxygen carrier) under the Food and Drug Administration’s compassionate use program. However, these measures were ultimately unnecessary because the reported surgery was uneventful. Another case at All India Institute of Medical Sciences, Bhopal, involved a 49-year-old woman with anemia, for whom no compatible donors were available. The patient was successfully managed with oral iron supplementation and close hemodynamic monitoring.¹³ In Nepal, an older gravida with placenta previa and O_h blood group underwent autologous blood donation at 35 weeks, with ongoing maternal and fetal surveillance.¹⁴ Although these reports demonstrate diverse and effective transfusion strategies, their applicability depends on clinical circumstances. In the present case, same approaches were unsuitable, as detailed in Table 1.

Most reported O_h blood group cases are detected during preoperative evaluations; however, this patient posed a major challenge for the blood center, with significant uncertainty in procuring blood components in urgency. Anticipating possible unavailability, our team implemented a carefully coordinated plan to ensure timely procurement. The scarcity of published guidance further complicates emergency transfusion management in rare blood groups. Overcoming such challenges requires expertise from transfusion medicine specialists, access to alternative products, and strategies to minimize transfusion needs, ensuring safe and timely patient care in critical situations.

This case underscores the urgent need for emergency strategies in managing transfusions for O_h blood group patients. Preemptive planning enhances disaster response by ensuring all team members are aligned with defined protocols. Early identification of potential donors, supported by an updated registry and mapping regional prevalence, can strengthen preparedness and guide targeted donor recruitment. Real-time communication and coordination between blood centers are vital to expedite access to rare blood products, preventing critical delays. Establishing a structured registry, alongside greater awareness and voluntary donor participation, can optimize procurement, strengthen transfusion logistics, and ultimately improve survival outcomes in emergency situations.

The authors thank all technicians and support staff of our Department of Transfusion Medicine as well as the nongovernmental organization staff who helped in procuring the products.

Contribution: B.S. and A.K. designed research, performed research, analyzed data, and wrote the manuscript; S.Saha. and S.O. designed research, supervised research, and edited the manuscript; and C.D. and S.Singh. performed research and analyzed data.

Conflict-of-interest disclosure: The authors declare no competing financial interests.

Correspondence: Aditi Khanna, Department of Transfusion Medicine, Tata Memorial Centre, Advanced Centre for Treatment, Research & Education in Cancer, A-501, Gandharwa Society, Omega1, Greater Noida, Uttar Pradesh 201308, India; email: aditi.khanna2803@gmail.com.