Transfusion Medicine and Blood Banking
Core concepts
Know the immunohaematology foundations: ABO and Rh systems, the principle of the antibody screen and crossmatch, and the significance of clinically significant alloantibodies (Rh, Kell, Duffy, Kidd). Understand the antibody detection phases (immediate spin, 37 °C incubation, antihuman globulin) and the direct antiglobulin test for immune haemolysis. Master compatibility logic: group O negative as the universal red cell for emergency, group AB plasma as universal plasma, and the need for antigen-negative units in alloimmunised patients.
Understand component therapy: packed red cells, platelets, fresh frozen plasma, cryoprecipitate, and their indications and thresholds. Know transfusion reactions and their timing: acute haemolytic (minutes, ABO incompatibility, fever, haemoglobinuria, DIC), febrile non-haemolytic, allergic/anaphylactic, transfusion-related acute lung injury (TRALI), transfusion-associated circulatory overload (TACO), and delayed haemolytic reactions (3–14 days). Understand bacterial contamination risk, especially platelets stored at room temperature.
Traps in questions
Do not give platelets for a low count without considering the cause and bleeding risk. TRALI is non-cardiogenic pulmonary oedema within 6 hours, often donor antibody-mediated; TACO is volume overload and responds to diuretics. A positive DAT does not always mean haemolysis. Emergency uncrossmatched blood still requires a pre-transfusion sample and a formal crossmatch afterwards.
Rule of thumb
For any transfusion reaction: stop the transfusion, maintain the line with saline, check clerical identity, and investigate haemolysis (repeat ABO, DAT, plasma free haemoglobin, repeat crossmatch).