COMPATIBILITY TESTING/PRE-TRANSFUSION TESTING

Question 1

Series of testing procedures and processes with the ultimate objective of ensuring the best possible results of a blood transfusion

Answer 1

Compatibility testing/Pre-transfusion testing

Question 2

Pre-transfusion testing should be performed on samples less than _____ hours

Answer 2

72 hours

Question 3

After testing, pre-transfusion samples must be stored for ___________ at 1-6C

Answer 3

at least 7 days

Question 4

Serological tests includes:

Answer 4

• Confirmation of ABO and Rh type
• Antibody screening/Ab identification
• Crossmatch

Question 5

Consists of mixing recipient plasma with cells directly obtained from the donor unit

Answer 5

Serologic Crossmatch

Question 6

Types of Serologic crossmatch:

Answer 6

1. Immediate spin crossmatch - centrifugation at room temperature; detects IgM abs
2. Antiglobulin crossmatch - principle: IAT (37C incubation) detects IgG abs

Question 7

ABO compatibility can be verified electronically via a validated, on-site computer system provided acceptable criteria have been met

Answer 7

Computer/Electronic crossmatch

Question 8

Acceptable criteria that a patient must possess to be eligible for Computer/Electronic crossmatch:

Answer 8

1. Two determinants of the recipient’s ABO grouping must be on file, one of which is from the current specimen collection
2. Recipient must not have detectable/history of clinically significant antibodies

Question 9

What is the purpose of Antibody Screening?

Answer 9

Detects unexpected antibodies present in 0.2-2% of general population (auto/alloantibodies) antibodies aside from ABO

Question 10

What is the purpose of Antibody identification?

Answer 10

Additional testing to identify the antibody and determine its clinical significance

Question 11

How many reagent vials of screening cells are used in antibody screening?

Answer 11

3 vials of panel/screening cells

Question 12

How many reagent vials of panel/screening cells are used in antibody identification?

Answer 12

11 vials of panel cells/screening cells

Question 13

What RBC type are panel/screening cell?

Answer 13

Type O Red Cells

screening/panel cells are type O red cells which are phenotyped for the most commonly encountered antigens

Question 14

Phases in Antibody screening and identification:

Answer 14

1. Immediate spin
2. Heat phase/Incubation phase (37C)
3. AHG phase

Question 15

used for validation purposes of antibody screening and identification:

Answer 15

Check cells/Coombs’ control

Question 16

Blood group antibodies detected in immediate spin phase:

Answer 16

ABO Abs - clinically significant
Anti-Lea, Anti-Leb
Anti-I, Anti-i
Anti-M, Anti-N
Anti-P1

They are all IgM antibodies

Question 17

Blood group antibodies detected in AHG phase

Answer 17

Rh Abs
anti-K
Anti- Fya, Anti-Fyb
Anti-Jka, Anti-Jkb
Anti-S, Anti-s, Anti-U
Anti-Lub

They are all IgG antibodies; clinically significant

Question 18

Inhibit antibody reactivity by mixing serum with a specific soluble antigen source

Answer 18

Hemagglutination inhibition

Note:
Soluble antigen and their source

ABH, Lea, Leb - Saliva from secretor
P1 - Hydatid cyst, pigeon eggs
Sda - Human/guinea pig urine
I - Human milk
Ch-Rg - Human plasma (+) Ch-Rg

Question 19

Adsorb serum antibodies with autologous cells or selected allogeneic cells

Answer 19

Serum adsorption

Question 20

Remove and recover antibody from surface of red cells

Answer 20

Elution

recovered Abs = eluate

Question 21

Partial elution reagents:

Answer 21

Chloroquine diphosphate
EDTA-glycine acid
Gentle heating at 45C

Question 22

Total elution reagents:

Answer 22

Organic solvents
Glycine acid solution (pH 3)
Heating at 56C

Question 23

Combination of DTT (dithiothreitol) and enzymes destroys coating of IgG autoantibodies

Answer 23

ZZAP

“AP” - activated papain