Blood Groups and Blood Transfusion Dr Stuart Laidlaw
Blood Groups and Blood Transfusion Dr Stuart Laidlaw Haematology Royal Hallamshire Hospital
Red blood cells • Provide intravascular volume and O 2 carrying capacity. • Transfusion of red cells can be life-saving in situations of acute intravascular volume loss, e. g. trauma, surgery
Red blood cells • Although red cells have a limited life-span, transfusion to another individual is a form of tissue transplantation, with similarities to kidney, heart and bone marrow transplantation • Compatibility between donor and recipient is vital or rejection will occur
Red Cells • Carry on the surface of their membrane many different proteins which differ between individuals • These are the red cell antigens • Inherited • Over 400 different systems of red cell antigens • Only 2 very important: ABO and Rhesus
ABO blood group system • 4 blood groups: A, B, AB and O • O is recessive, so O = 0, 0 • A= AA or AO, B=BB or BO, AB= AB O= 45%, A= 40%, B=12%, AB= 3%
ABO blood group system • ABO unusual antigens: carbohydrate, not protein • Naturally occuring antibodies from age 6 months • Ig. M antibodies in plasma, don’t cross placenta • Ig. M antibodies fix complement to C 9, so transfusion reactions very severe
ABO blood group • Can type cells as A, B or AB, using antibodies: anti-A and anti-B. If react with neither =group O • Can type serum as double check O serum will contain anti-A and anti-B AB serum will not contain any antibody A will contain anti-B, B will contain anti-A
Rhesus blood group system • Complex series of C, D and E antigens • D/d by far most important • D is a null gene, no protein product, so no anti-d possible • D is dominant, so D = DD or Dd • 15% population dd = d negative
Rhesus blood group system • Women who are rhesus negative (dd) have babies that carry paternal antigens, such as D. • If mother exposed to D red cells will make Ig. G anti-D • Anti-D crosses placenta and haemolyses babies red cells: can result in in-utero death and need for in-utero blood transfusion
Rhesus blood group • It is so vital that women of childbearing age are not exposed to wrong rhesus type blood that everyone receives rhesus, as well as ABO, compatible blood. • All women have rhesus blood type determined at each conception. • Anti-D given to D negative mothers to prevent sensitisation
Other blood groups • Many in number • Infrequent problem • Only likely to have been sensitised if had previous blood transfusion (occasionally by pregnancy) • Can cause major problems with finding compatible blood
Group and Save • Determine ABO group: cells and serum • Determine Rh D status, using two different reagents • Screen serum for presence of preformed antibodies to any blood group
Cross match • Specifically determine compatibility between donor red cells and recipients serum • Very important if known antibodies or multiple previous transfusions • If group and screen neg X 2 may be unnecessary, use electronic cross-match
Indications for transfusion • Hypovolaemia due to loss blood • Severe anaemia with symptoms due to inadequate oxygenation of tissues • Anaemia that cannot be corrected by bone marrow function
Indications for transfusion • Not indicated for iron deficiency or B 12/ folate deficiency. • Not indicated for minor blood loss, especially if fit and healthy (transfusion trigger = 8 g/dl) • Not indicated for asymptomatic anaemia
Hazards of transfusion • Blood is tissue from another individual • Transfusion is potentially fatal, although used properly can, and does save lives
Early hazards • ABO incompatibility reaction – can be rapidly fatal • Fluid overload, pulmonary oedema • Febrile reactions, urticarial reactions, occasionally life threatening respiratory failure • Bacterial and malerial infection
Late hazards • • • Rh D and other antibody sensitisation Delayed transfusion reaction Viral infection: Hepatitis B, C, HIV ? Prion infection: nv. CJD Iron overload: cardiac, hepatic and endocrine damage
Alternatives to transfusion • Treat anaemia pre-op • Use transfusion trigger • Stop anti-platelet and anti-coagulant drugs • Consider intra-operative cell salvage and reinfusion
Alternatives to transfusion • Consider pre-and post- operative erythropoietin • Consider individual pre-donation of red cells • Currently no universally available alternatives to blood ? O 2 carrying solutions, ? Artificial/ recombinant haemoglobin polymers
Other components • Blood is not only red cells • Also platelets and plasma • Plasma can be used as it is, or fractionated to produce concentrates of specific components, e. g. factor VIII or IX • White cells only rarely used, as antibiotics so potent!
Fresh frozen plasma • Plasma frozen within 6 hours of collection • Contains all the coagulation proteins and inhibitors • Used if massive transfusion and dilutional coagulopathy, in liver disease and DIC
Cryoprecipitate • Rich in fibrinogen • Used in DIC and massive transfusion if specific lack of fibrinogen
Platelets • Correct bleeding due to thrombocytopenia • Work for lack of production or perippheral consumption • Not useful if deficiency is due to immune anti-platelet antibody
Albumin • Useful if oedema due to lack oncotic pressure in liver disease or nephrotic syndrome • Use currently declining rapidly
Anti-D globulin • Collected from people deliberately sensitised to D • Used to prevent Rh D disease in Rh d women in pregnancy, after childbirth, miscarriage, abdominal trauma in pregnancy and TOP
Intravenous immunoglobulin • Pooled immunoglobulin • Used for immunodeficiency, congenital or acquired • Used in some auto-immune diseases
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