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Background The limited supply of universal plasma has resulted in transfusion of ABO incompatible plasma to patients. As the need to implement whole blood transfusion in pre-hospitals setting rises, the lowest cut-off for anti-A/anti-B that does not cause haemolysis remains unknown. In this first scoping review, we aimed to determine the lowest ABO titre and volume reported in the literature to cause haemolysis from ABO incompatible plasma transfusions (plasma, platelets, cryoprecipitate, and whole blood). Methods We searched several databases from inception to April 2022, including all study types. Three independent reviewers extracted and reviewed the data. Primary outcome was the anti-A and anti-B titre (measured by IgM or IgG) that resulted in measurable haemolysis following ABO incompatible plasma transfusion. Results We identified 5681 citations, of which 49 studies were eligible, reporting a total of 62 cases (34 adults, 14 children and 14 did not specify age). The methods for antibody measurement and antibody type (IgG or IgM) varied significantly between studies. Component volumes were poorly reported. The most common component responsible for the haemolysis was apheresis platelets followed by pooled platelets and whole blood. Most haemolytic cases reported were due to anti-A. The lowest anti-A titre reported to cause haemolysis (children and adults) was 32 (IgG), while for anti-B it was 512 (IgG and IgM) for adults, 16,384 for paediatrics (IgG and IgM) and 128 (IgM) in cases where the age was not specified. The lowest reported volume associated with haemolysis were 100 ml (adults) and 15 ml (children). Of the 62 15 (24%) died. Conclusion The lowest titre reported to cause haemolysis was an anti-A of 32. ABO mismatch plasma transfusion may be associated with significant mortality. There is a need to agree/standardise methods for ABO titration measurement internationally for plasma components and agree the lowest anti-A/anti-B titre for transfusing ABO mismatched plasma.

Original publication




Journal article


Blood Rev

Publication Date





ABO incompatible, Anti-A, Anti-B, Haemolysis, Plasma, Platelets, Titre, Transfusion, Volume, Adult, Humans, Child, Blood Group Incompatibility, Hemolysis, ABO Blood-Group System, Blood Component Transfusion, Plasma, Transfusion Reaction, Blood Transfusion, Anemia, Hemolytic, Autoimmune, Immunoglobulin G, Immunoglobulin M