Blood bank 4.5 Compatibility Testing

Question 1

1. SITUATION: An emergency trauma patient requires transfusion. Six units of blood are ordered stat (immediately). There is no time to draw a patient sample. O-negative blood is issued. When will compatibility testing be performed?

A. Compatibility testing must be performed before blood is issued
B. Compatibility testing will be performed when a patient sample is available
C. Compatibility testing may be performed immediately by using donor serum
D. Compatibility testing is not necessary when blood is issued in emergency situations

Answer 1

B. Compatibility testing will be performed when a patient sample is available

Question 2

2. How would autoantibodies affect compatibility testing?
   A. No effect
   B. The DAT result would be positive
   C. ABO, Rh, antibody screen, and crossmatching may show abnormal results
   D. Results would depend on the specificity of autoantibody

Answer 2

C. ABO, Rh, antibody screen, and crossmatching may show abnormal results

Question 3

3. An antibody screen is reactive at the IAT phase of testing with all three cells of a three-cell screen, and the autocontrol is negative. What is a possible explanation for these results?
   A. A cold alloantibody
   B. High-frequency alloantibody or a mixture of alloantibodies
   C. A warm autoantibody
   D. A cold and warm alloantibody

Answer 3

B. High-frequency alloantibody or a mixture of alloantibodies

Question 4

4. What does a minor crossmatch consist of?
   A. Recipient plasma and recipient RBCs
   B. Recipient plasma and donor RBCs
   C. Recipient RBCs and donor plasma
   D. Donor plasma and donor RBCs

Answer 4

C. Recipient RBCs and donor plasma

Question 5

5. Can crossmatching be performed on October 14 using a patient sample drawn on October 12?
   A. Yes, a new sample would not be needed
   B. Yes, but only if the previous sample has no alloantibodies
   C. No, a new sample is needed because the 2-day limit has expired
   D. No, a new sample is needed for each testing

Answer 5

A. Yes, a new sample would not be needed

Question 6

6. A type and screen was performed on a 32-year-old woman, and the patient was typed as AB negative. There are no AB-negative units in the blood bank. What should be done?
   A. Order AB-negative units from a blood supplier
   B. Check inventory of A-, B-, and O-negative units
   C. Ask the patient to make a preoperative autologous donation
   D. Nothing—the blood will probably not be used

Answer 6

B. Check inventory of A-, B-, and O-negative units

Question 7

7. What ABO types may donate to any other ABO type?
   A. A negative, B negative, AB negative, O negative
   B. O negative
   C. AB negative
   D. AB negative, A negative, B negative

Answer 7

B. O negative

Question 8

8. What type(s) of RBC(s) is (are) acceptable to transfuse to an O-negative patient?
   A. A negative, B negative, AB negative, or O negative
   B. O negative
   C. AB negative
   D. AB negative, A negative, B negative

Answer 8

B. O negative

Question 9

9. An MLS removed 4 units of blood from the blood bank refrigerator and placed them on the counter. A clerk was waiting to take the units for transfusion. As she checked the paperwork, she noticed that one of the units was leaking onto the counter. What should she do?
   A. Issue the unit if the RBCs appear normal
   B. Reseal the unit
   C. Discard the unit
   D. Call the medical director and ask for an opinion

Answer 9

C. Discard the unit

Question 10

10. A donor was found to contain anti-K using pilot tubes from the collection procedure. How would this affect the compatibility test?

A. The AHG major crossmatch would be positive
B. The IS major crossmatch would be positive
C. The recipient’s antibody screen would be positive for anti-K
D. Compatibility testing would not be affected

Answer 10

D. Compatibility testing would not be affected

Question 11

11. Which of the following is not a requirement for electronic crossmatching?
    A. The computer system contains logic to prevent assignment and release of ABO incompatible blood
    B. There are concordant results of at least two determinations of the recipient’s ABO type on record, one of which is from the current sample
    C. Critical elements of the system have been validated on site
    D. There are concordant results of at least one determination of the recipient’s ABO type on file

Answer 11

D. There are concordant results of at least one determination of the recipient’s ABO type on file

Question 12

12. A patient showed positive results with screening cells and 4 donor units. The patient autocontrol was negative. What is the most likely antibody?
    A. Anti-H
    B. Anti-S
    C. Anti-Kpa
    D. Anti-k

Answer 12

D. Anti-k

Question 13

13. Screening cells and major crossmatch are positive on IS only, and the autocontrol is negative. Identify the problem.
    A. Cold alloantibody
    B. Cold autoantibody
    C. Abnormal protein
    D. Antibody mixture

Answer 13

A. Cold alloantibody

Question 14

14. Six units are crossmatched. Five units are compatible, one unit is incompatible, and the recipient’s antibody screen is negative. Identify the problem:
    A. Patient may have an alloantibody to a high-frequency antigen
    B. Patient may have an abnormal protein
    C. Donor unit may have a positive DAT
    D. Donor may have a high-frequency antigen

Answer 14

C. Donor unit may have a positive DAT

Question 15

15. An incompatible donor unit is found to have a positive result on DAT. What should be done with the donor unit?
    A. Discard the unit
    B. Antigen type the unit for high-frequency antigens
    C. Wash the donor cells and use the washed cells for testing
    D. Perform a panel on the incompatible unit

Answer 15

A. Discard the unit

Question 16

16. Screening cells, major crossmatch, and patient autocontrol are positive in all phases. Identify the problem.
    A. Specific cold alloantibody
    B. Specific cold autoantibody
    C. Abnormal protein or nonspecific autoantibody
    D. Cold and warm alloantibody mixture

Answer 16

C. Abnormal protein or nonspecific autoantibody

Question 17

17. A panel study has revealed the presence of patient alloantibodies. What is the first step in a major crossmatch?
    A. Perform a DAT on patient cells and donor units
    B. Antigen type patient cells and any donor cells to be crossmatched
    C. Adsorb any antibodies from patient serum
    D. Obtain a different enhancement medium for testing

Answer 17

B. Antigen type patient cells and any donor cells to be crossmatched

Question 18

18. What is the disposition of a donor RBC unit that contains an antibody?
    A. The unit must be discarded
    B. Only the plasma may be used to make components
    C. The antibody must be adsorbed from the unit
    D. The unit may be labeled to indicate that it contains antibody and released into inventory

Answer 18

D. The unit may be labeled to indicate that it contains antibody and released into inventory

Question 19

19. Given a situation where screening cells, major crossmatch, autocontrol, and DAT (anti-IgG) are all positive, what procedure should be performed next?
    A. Adsorption using rabbit stroma
    B. Antigen typing of patient cells
    C. Elution followed by a cell panel on the eluate
    D. Selected cell panel

Answer 19

C. Elution followed by a cell panel on the eluate

Question 20

20. A major crossmatch and screening cells are 2+ at the IS phase, 1+ at 37°C, and negative at the IAT phase. Identify the most likely problem.
    A. Combination of antibodies
    B. Cold alloantibody
    C. Rouleaux
    D. Test error

Answer 20

B. Cold alloantibody

The reaction pattern fits that of a cold antibody reacting at the IS phase and of sufficient titer to persist at 37°C incubation. The reactions disappear in the IAT phase.

Question 21

21. What corrective action should be taken when rouleaux causes positive test results?
    A. Perform a saline replacement technique
    B. Perform an autoabsorption
    C. Run a panel
    D. Perform an elution

Answer 21

A. Perform a saline replacement technique

Question 22

22. All of the following are reasons for performing an adsorption, except:
    A. Separation of mixtures of antibodies
    B. Removal of interfering substances
    C. Confirmation of weak antigens on RBCs
    D. Identification of antibodies causing a positive DAT

Answer 22

D. Identification of antibodies causing a positive DAT

Antibodies causing a positive DAT would be coating RBCs and would require elution, not adsorption, to identify them.

Question 23

23. How long must a recipient sample be kept in the blood bank after compatibility testing?
    A. 3 days
    B. 5 days
    C. 7 days
    D. 10 days

Answer 23

C. 7 days

Question 24

24. What is the crossmatching protocol for platelets and/or plasma?
    A. Perform a reverse grouping on donor plasma
    B. No testing is required
    C. Perform a reverse grouping on recipient plasma
    D. Platelets must be HLA compatible

Answer 24

B. No testing is required

Question 25

25. What are the compatibility requirements for an autologous unit? A. ABO and Rh typing B. Type and screen C. Major crossmatch D. All of these options

Answer 25

A. ABO and Rh typing

Question 26

26. A patient is typed as AB positive. Two units of blood have been ordered by the physician. Currently, the inventory shows no AB units, 10 A-positive units, 1 A-negative unit, 5 B-positive units, and 20 O-positive units. Which should be set up for the major crossmatch? A. A-positive units B. O-positive units C. B-positive units D. Call another blood supplier for type-specific blood

Answer 26

A. A-positive units The type chosen should be A-positive RBC units. Although all choices would be compatible, the first choice should be A-positive because this unit will contain residual plasma anti-B. Anti-B is less immunogenic than anti-A, which would be present, albeit in small amounts, in B-positive and O-positive units.

Question 27

27. Which of the following comprises an abbreviated crossmatch? A. ABO, Rh, and antibody screen B. ABO, Rh, antibody screen, IS crossmatch C. Type and screen D. ABO, Rh, IS crossmatch

Answer 27

B. ABO, Rh, antibody screen, IS crossmatch

Question 28

28. When may IS crossmatching be performed? A. When a patient is being massively transfused B. When there is no history of antibodies and the current antibody screen is negative C. When blood is being emergency released D. When a patient has not been transfused in the past 3 months

Answer 28

B. When there is no history of antibodies and the current antibody screen is negative