Compatibility Testing

Blood transfusions – who can receive blood from whom? Blood Group Antigens Antibodies Can give blood to Can receive blood from AB A and B None AB, A, B, O A B A and AB A and O B and AB B and O O

Blood can be received from: Rh Blood Groups Blood Type Rh Antigen Blood can be received from: Rh +ve Rh antigen present Rh + ve AND Rh - ve Rh –ve Rh antigen absent Rh -ve 3

O A B AB People with blood group O are called "universal donors" People with blood group AB are called "universal receivers." A B O AB Universal Donor Universal Recipient

Antibody clinical significance If an individual is transfused with an incompatible blood group destruction of the RBC will occur. This may result in the death of the recipient.

Transfusion Reactions Transfusion reactions occur when mismatched blood is infused Donor’s cells are attacked by the recipient’s plasma agglutinins.

What is compatibility testing? Also called pre-transfusion testing Purpose: To select blood components that will not cause harm to the recipient and will have acceptable survival when transfused

Compatibility testing Can be divided into 3 categories: Pre-analytical procedures Serological testing Pos-tanalytical procedures

Pre-analytical phases Patient identification Specimen collection Review of patient history

Patient Identification Must confirm recipient’s ID from bracelet ON the patient Full patient name and hospital number Name of physician

Sample Identification The sample should also have the full patient name, hospital number, and physician Date and time of collection, phlebotomist’s name All of this should be on the request form and the sample

Specimen Collection Collected in tube with EDTA. If the venipuncture causes hemolysis, the sample is rejected. Samples are labeled at the bedside . Testing should be performed on samples less than 72 hours

Getting the history Look at recipient’s records for any prior unexpected antibodies Previous transfusion reactions

Serological Testing Three tests: ABO/Rh Antibody detection/identification Crossmatch

Test for transfusion Antibody Screen is a test that is always performed on patients who may require red blood cell transfusion, and this test will detect most clinically significant red cell antibodies.

Crossmatching Purpose: Prevent transfusion reactions Increase in vivo survival of red cells Double checks for ABO errors Another method of detecting antibodies

Crossmatch No agglutination (compatible) Agglutination (incompatible) Donor RBCs (washed) Patient serum

Routine Crossmatching This consists of testing the patient’s serum or plasma against donor red cells by: 1-Direct agglutination test, called immediate Spin technique, in which we just mixture of recipient serum and donor cells for 5 minutes at room temperature, followed by centrifugation at 200 g for 30 seconds and then checking for agglutination.

Routine Crossmatching 2- Indirect agglutination test (IAT), the IAT tubes are left for 45-60 minutes incubating at 37 oC , they are then taken out washed four times in normal saline and then two drops of Antihuman globulin (AHG) is added and mixed, followed by centrifugation for 30 seconds art 200 g, and then checking for agglutination.

The procedure Donor cells are taken from segments that are attached to the unit itself Segments are a sampling of the blood and eliminate having to open the actual unit

Post-analytical phase Labeling form includes patient’s full name, ID number, ABO/Rh of patient and unit, donor #, compatibility results. The unit is visually inspected for abnormalities, such as bacterial contamination, clots, etc

Wha can be given in an emergency? Group O Rh-negative red cells or AB plasma Emergency release Women below or of childbearing age Or if in doubt