Patient identification is the most crucial step in compatibility testing and a common type of error
Serum is the preferred specimen for compatibility testing.
Hemolysis should be avoided
Plasma is not used in compatibility testing because it may cause small fibrin clots to form which may be difficult to distinguish from true agglutination.
It may also inactivate complement so that antibodies may not be detected.
The freshest sample possible should be used for compatibility testing.
Specimens must be less than 3 days old if the patient has been transfused or pregnant within the past 3 months.
Sample storage in compatibility testing
The AABB requires that patient samples must be stored between 1-6 °C for at least 7 days after transfusion
ABO grouping is the most critical pretransfusion serologic test in compatibility testing
If the patient’s ABO group cannot be satisfactorily determined and immediate transfusion is essential, group O packed red cells should be utilized.
If Rh type of the recipient cannot be determined and transfusion is essential, Rh-negative blood should be given
Crossmatching
Major X-match = Donor’s cells + Recipient’s serum
Minor X-match = Donor’s serum + Recipient’s cells
The purpose of crossmatching is to final check the ABO compatibility between patient and donor to prevent transfusion reaction.
It detects the presence of antibody in patient’s serum that will react to donor’s RBC that is not detected in antibody screen.
3 phases of crossmatching
Immediate Spin in saline at room temp
detects IgM
Thermophase or 37°C incubation for 30 minutes with enhancement medium such as albumin, LISS, PEG
detects IgG
AHG Phase after washing incubated cells with saline
In phases of crossmatching, Check cells or Coombs control cells (IgG sensitized cells) should be added to tubes that demonstrate no agglutination
For results to be considered valid in crossmatching, agglutination must occur.
A compatible crossmatch is indicated by absence of agglutination and/or hemolysis at any stage of the crossmatch.
The absence of agglutination indicates that the patient has no demonstrable antibodies with specificity for any antigen on donor’s RBC.
A) ABO/Rh typing
B) + DAT
C) Low incidence Ab
A) Alloantibody
A) Autoantibody
B) Roleaux
Blood substitutes are substances that is able to carry oxygen in the absence of intact red cells
Stroma-free Hemoglobin solutions or Hemoglobin-based Oxygen Carriers
Perfluorochemicals are excellent gas (O2 and CO2) solvents
Transfusion therapy or lesion of storage
Autologous transfusion is a donation of blood by patients for transfusion to themselves in the future
Emergency transfusion is given to patients who are bleeding rapidly and uncontrollable.
Group O negative units should be used especially if the patient is a woman of childbearing years
Massive transfusion is defined as the replacement of one or more blood volume/s within 24 hours or about 10 units of blood in an adult
Premature infants frequently require transfusion of small amounts of blood to replace blood drawn for laboratory tests, called Neonatal transfusion
Blood units less than 5 days old are preferred to lessen the risk of hyperkalemia and to maximize the 2,3 DPG levels
Acute/Immediate hemolytic transfusion reaction is the most severe and may be life threatening due to ABO incompatibilities
Most severe cases may results to DIC and Renal Failure
Acute/Immediate hemolytic transfusion reaction
The associated hemolysis is intravascular
Mediators: IgM Abs (usually to ABO antigens), complement
Febrile nonhemolytic transfusion reaction increases temperature of greater than 1°C after transfusion; mild immunologic reactions that are caused by the interaction of recipient antibodies against HLS Antigens on Donor’s WBC and platelets
Most common S/S: fever and chills
Management/prevention: use of leukocyte filters during transfusion; Antipyretic
Allergic transfusion reaction is the second most common type of transfusion reactions
Management/Prevention: Administration of Antihistamines before the transfusion
Anaphylactic transfusion reaction
Mediator: plasma proteins, antibodies to IgA
M/P: transfusion of IgA-deficient compounds
In Noncardiogenic pulmonary edema, most consistent finding is Anti-leukocyte Abs in donor or patient plasma
Good example of iatrogenic transfusion reaction is transfusion associated circulatory overload
Common in patients with cardiac and pulmonary disease
May lead to congestive heart failure and pulmonary edema
Delayed hemolytic transfusion reaction is characterized by the accelerated destruction of transfused RBCs
most commonly associated with a secondary response
Delayed hemolytic transfusion
The associated hemolysis is generally Extravascular
Mediators: IgG Abs to Rh, MNS, Kell, Kidd and Duffy antigens
Transfusion associated Graft vs. Host disease occurs when immunologically competent lymphocytes are transfused into an immunocompromised host.
S/S: Fever, liver problems, rash and diarrhea
M/P: transfusion of irradiated blood components
Graft vs. host disease occurs when white blood cell in transfused blood attack the tissues of a transfusion recipient who has a severely weakened immune
To prevent WBC from causing GVHD, donated blood can be treated with radiation before transfusion
Post-transfusion purpura is a rare transfusion reaction usually seen in older female patients who have been sensitized to platelet antigens, either by previous pregnancy or transfusion.
Characterized by severe thrombocytopenia one week after transfusion due to antibody to platelet specific antigen
Transfusion-induced Hemosiderosis is the iron deposition in vital organs seen in patients who are thalassemics and with chronic transfusions
Transfusion of stored blood has not been shown to transmit syphilis because spirochetes do not survive at ref temp for 72 hours