Abstract
Transfusion Service
Kristina Prus, MD (she/her/hers)
Director of Transfusion Services, Section Director of Clinical Coagulation Testing Laboratory, Medical Director of the Cellular Manipulation Laboratory
Cincinnati Children's Hospital Medical Center
Cincinnati, Ohio, United States
Disclosure information not submitted.
The risk of alloimmunization against the D antigen in patients who are RhD-negative and receive RhD-positive apheresis platelets is controversial with varying practices across institutions. Apheresis platelets contain a lower volume of residual red blood cells as compared to whole blood derived platelets and have a red blood cell content below the threshold believed to cause alloimmunization. Rh Immune Globulin (RhIg) is used by some for these incompatible transfusions, but this medication is costly and can be subject to shortages. Studies analyzing the effects of an Rh-incompatible apheresis platelet transfusion without RhIg are lacking.
Study
Design/Methods:
A retrospective chart review of electronic health records from the hospital and laboratory information systems was performed. All RhD-negative pediatric, adolescent, and young adults aged 0-39 years who received at least one RhD-positive apheresis platelet from April 1, 2021 to April 1, 2024 were reviewed after IRB approval. Individuals were excluded if they received RhD-positive red cell containing components during the study period or did not have an antibody screen at least seven days after transfusion of an RhD-positive apheresis platelet product.
Results/Findings:
A total of 1220 products were transfused to 111 individuals who had an RhD-negative blood type and at least one RhD-positive platelet transfusion with a follow up antibody screen. There were no cases of an anti-D developing after transfusion. One anti-D was identified during the study which was present prior to platelet transfusion. The length of post-transfusion antibody screen ranged from 7 to 1038 days (average 167 days, median 214 days). Seven individuals had an antibody to other antigens, including passive anti-D (4), warm autoantibody (2), E (1), unidentified (2), C (1), and Fya (1). All instances of passive anti-D occurred prior to a platelet transfusion. Eight individuals had a transfusion reaction including febrile non-hemolytic (FNHRT) (5), allergic (2), and transfusion-associated circulatory overload (1). Two individuals had multiple FNHTR reactions, one with five and one with three. Median age of individuals was 6 years, ranging from 0-39 years with an average age of 9.6 years. Just over half of individuals had a history of immunosuppressive medications (62%, n=69).
Conclusions:
Transfusion of RhD-positive apheresis platelet units to RhD-negative patients has a low likelihood of an alloimmunization event. In a review of 111 individuals in a large pediatric academic hospital, no anti-D antibodies were found due to incompatible apheresis platelet transfusions. Due to inventory constraints, it is not always feasible to transfuse RH matched apheresis platelets to all patients. Platelets are likely able to be transfused to any patient regardless of RhD, if they are collected by an apheresis method, without any additional interventions.