5. Pretransfusion testing

Question 1

6 crucial steps for safe transfusion

Answer 1

1. ID of patient and donor with appropriate sample collection
2. Testing of donor sample
3. Testing of patient sample and patient history review
4. Selection of appropriate units
5. Crossmatch
6. Re-identification of patient before infusion

Question 2

circle of safe transfusion

Answer 2

Patient wristband → BB sample → crossmatched units → transfusion request record → patient wristband

Question 3

sample condition requirements (5)

Answer 3

1. labelled correctly (2 identifiers); date; phlebotomist’s ID
2. sufficient quantity
3. minimal hemolysis
4. appropriate site (not above IV)
5. indelible ink used

Question 4

records kept indefinitely

Answer 4

any difficulty in typing
clinically significant Abs

Question 5

I, II and III screening cells are type — and have at least one cell…

Answer 5

O
homozygous for all clinically significant Abs

Question 6

selection of appropriate units

Answer 6

• type-specific preferred
• use short-dated
• conserve O for O patients

Question 7

preferred form of XM

Answer 7

EXM

Question 8

You can stop XM after negative IS or EXM if…

Answer 8

negative ABS
no hx of significant Ab

Question 9

serves as final check for ABO/Rh compatibility

Answer 9

XM

Question 10

major XM

Answer 10

pt plasma + donor cells

Question 11

minor XM

Answer 11

donor plasma + pt cells

Question 12

often to blame for XM incompatibility

Answer 12

autoAB

Question 13

potential reasons for XM incompatibility (5)

Answer 13

• autoAb
• alloAb
• error in unit selection/typing
• excessive protein in pt serum
• contaminants in test system

Question 14

in emergencies, O= is given to….

Answer 14

females
males < 12 yo

Question 15

in emergencies, O+ is given to…

Answer 15

males > 12 yo

Question 16

Rh= patients that may receive Rh+ blood with pathologist approval

Answer 16

adult males
females > 50yo

Question 17

included on blood transfusion request form (4)

Answer 17

Pt 2 identifiers
Product requested
Physician
Transporter to patient care area

Question 18

included on label on issued units (3)

Answer 18

ID of intended recipient
Statement of compatibility
Unit or pool number

Question 19

read back includes… (5)

Answer 19

Intended recipient’s 2 IDs and ABO/Rh
Donor unit number and ABO/Rh
XM interpretation, if required
Special requirements
Date and time of issue (expiration)

Question 20

type for patient w/o hx of type

Answer 20

checktype

Question 21

reflex ABS procedures

Answer 21

ABS panel
antigen typing
2-unit XM (if sample labelled for transfusion)

Question 22

miniature automated tube tests

Answer 22

microtiter plate

Question 23

solid phase measures…

Answer 23

adherence of analyte to solid phase

Question 24

SPRCA

Answer 24

solid phase red cell adherence

Question 25

in solid phase, patient plasma is incubated with —— on a tray of wells containing….

Answer 25

LISS
bound known antigen

Question 26

added after incubation and washing of solid phase plate
why?

Answer 26

indicator cells with anti-IgG
allow visualization of Ab from plasma bound to antigen in solid phase

Question 27

solid phase plate is incubated at —– for —– mins

Answer 27

37°
30 mins

Question 28

positive solid phase reaction

Answer 28

indicator cells adhere to wells

Question 29

negative solid phase reaction

Answer 29

cell button; no adherence of indicator cells

Question 30

tests performed in solid phase in a well that is activated only

Answer 30

DAT
weak D
XM

Question 31

how is solid phase for XM, DAT, and weak-D different?

Answer 31

cells adhere to wall

pt plasma is added for XM
anti-D is added for weak D
indicator cells are added for DAT

Question 32

gel technology principle

Answer 32

antigen is suspended in gel medium
red cell agglutinates stay near top; nonagglutinated red cells pass through to the bottom

Question 33

how are gel IAT and gel DAT different?

Answer 33

IAT: IgG is in the gel
DAT: anti-IgG is in the gel (no C3)

Question 34

advantages of alternative tech (7)

Answer 34

• Standardized technique – consistent, reproducible and stable end points
• Less subjectivity
• Stability of test results
• Decreased sample volume
• Enhanced or equivalent sensitivity
• Automation is available
• Larger batches (ie Red Cross)

Question 35

disadvantages of alternative tech (7)

Answer 35

• Cost (equipment, training, reagents, etc)
• Some methods do not allow detection of both IgM and IgG, or cannot distinguish between them (ie Gel)
• Gel has difficulty with rouleaux, fibrin — false positives
• May not provide information on the phase and temperature of reactivity of antibodies
• Increased sensitivity my cause insignificant antibodies to be detected
• Solid phase requires a wash step
• Long TAT, especially with gel