transfusions

Transfusions involve transferring blood or components from a donor to a recipient to replace loss or treat hematologic conditions. The main components used are red blood cells, plasma, platelets, and cryoprecipitate; whole blood is rarely used today except in specific settings. Transfusions are common in cases of severe bleeding, surgery, trauma, anemia, or clotting disorders.

Compatibility testing and screening occur before a transfusion. Blood is typed for ABO and Rh(D); the recipient's serum is crossmatched with donor cells to reduce hemolytic risk. Donor blood is screened for infectious diseases and may be processed to reduce alloimmunization. In some patients, leukoreduced or irradiated components or antigen-matched platelets are used.

Risks include transfusion reactions (allergic, febrile, hemolytic), transfusion-related acute lung injury, transfusion-associated circulatory overload, iron overload with repeated transfusions, and alloimmunization. Infections are rare but possible. Special cases include autologous transfusion, where a patient donates before surgery, and intraoperative cell salvage.

Alternatives to transfusion include iron therapy, erythropoiesis-stimulating agents, and pharmacologic hemostasis when feasible.

Storage and logistics involve collection, testing, component separation, and regulated storage. Red cells are stored refrigerated up to about 42 days; platelets about 5 days; plasma can be stored long-term after freezing. Ethical and supply considerations reflect donor safety, eligibility, and the availability of adequate blood supplies.