There are many different types of transfusion reactions, which can be subdivided in several ways, according to their occurrence, pathogenesis and/or their symptomatology. A common subdivision based on the time to the occurrence is between acute (< 24 h after) and delayed (> 24 h after transfusion) reactions. According their pathogenesis, adverse reactions can be divided in infectious and non-infectious adverse reactions. Non-infectious acute reactions include: allergic reactions including anaphylactic reactions (AR), febrile non-haemolytic transfusion reactions (FNHTR), acute haemolytic transfusion reactions (AHTR), transfusion-associated acute lung injury (TRALI), transfusion-associated circulatory overload (TACO), hypotensive reactions and transfusion-associated hyperkalemia (TAH). Non-infectious delayed transfusion reactions include delayed haemolytic transfusion reactions (DHTR), delayed serologic transfusion reactions (DSTR), post-transfusion purpura (PTP), transfusion-associated graft versus host disease (TAGVHD), transfusion-associated necrotising enterocolitis (TANE) and Iron Overload. These can be caused by any of the blood components being transfused such as red cells, platelets or plasma. Some can also be caused by fractionated plasma components such as intravenous immunoglobulin (IVIg) or cryoprecipitate. The prevalence of these reactions has been estimated (57).
