Transfusing selected RhD negative patients with RhD positive packed red cell concentrates resulted in lower frequency of anti-D development and saved almost two thousand RhD negative concentrates during 5 years.

Background: The Blood Bank at Oslo University Hospital implements restrictions when the stocks of blood groups O and A RhD negative packed red blood cell concentrates (PRBCCs) drop below 60 units due to high demand and low donor availability. Restrictions entail transfusing RhD negative male patients and women >50 years with RhD positive units, to provide RhD negative units to those who should not receive RhD positive units. Earlier studies have reported that up to 50% of RhD negative patients developed anti-D after RhD positive blood transfusion. We aimed to investigate the rate of anti-D alloimmunization using this restriction strategy in our population.

Study design and methods: This retrospective study was performed at Oslo University Hospital between 2006 and 2011. Antibody screen results were included throughout 2019 for the patients readmitted to the hospital.

Results: 607 RhD negative mostly cancer patients and patients having surgery for cardiovascular conditions received 1926 RhD positive PRBCCs. Post-transfusion antibody screen was available for 401 patients (66.1%), and 76 patients (22.2%) developed anti-D. In 15 of the 76 patients (19.7%), anti-D became evanescent in the follow-up.

Discussion: The proportion of anti-D immunisation in RhD negative patients receiving RhD positive PRBCCs in this study was consistent with findings from other reports. To our knowledge, this is the first study reporting a high proportion of evanescence of anti-D. Transfusing selected RhD negative patients with RhD positive PRBCCs when RhD negative stocks are low, contributed saving 1926 RhD negative PRBCCs during the study period of 64 months.