<Li> Leukocyte reduction is the removal of white blood cells by filtration . Leukoreduced blood products are less likely to cause HLA alloimmunization (development of antibodies against specific blood types), febrile non-hemolytic transfusion reaction, cytomegalovirus infection, and platelet - transfusion refractoriness . </Li> <Li> Pathogen Reduction treatment that involves, for example, the addition of riboflavin with subsequent exposure to UV light has been shown to be effective in inactivating pathogens (viruses, bacteria, parasites and white blood cells) in blood products . By inactivating white blood cells in donated blood products, riboflavin and UV light treatment can also replace gamma - irradiation as a method to prevent graft - versus - host disease (TA - GvHD). </Li> <P> Before a recipient receives a transfusion, compatibility testing between donor and recipient blood must be done . The first step before a transfusion is given is to type and screen the recipient's blood . Typing of recipient's blood determines the ABO and Rh status . The sample is then screened for any alloantibodies that may react with donor blood . It takes about 45 minutes to complete (depending on the method used). The blood bank scientist also checks for special requirements of the patient (e.g. need for washed, irradiated or CMV negative blood) and the history of the patient to see if they have previously identified antibodies and any other serological anomalies . </P> <P> A positive screen warrants an antibody panel / investigation to determine if it is clinically significant . An antibody panel consists of commercially prepared group O red cell suspensions from donors that have been phenotyped for antigens that correspond to commonly encountered and clinically significant alloantibodies . Donor cells may have heterozygous (e.g. K + k −), homozygous (K + k+) expression or no expression of various antigens (K − k −). The phenotypes of all the donor cells being tested are shown in a chart . The patient's serum is tested against the various donor cells . Based on the reactions of the patient's serum against the donor cells, a pattern will emerge to confirm the presence of one or more antibodies . Not all antibodies are clinically significant (i.e. cause transfusion reactions, HDN, etc .). Once the patient has developed a clinically significant antibody it is vital that the patient receive antigen - negative red blood cells to prevent future transfusion reactions . A direct antiglobulin test (Coombs test) is also performed as part of the antibody investigation . </P>

How much blood can be transfused at one time