4.5 Compatibility Testing

Question 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?

Answer 1

Compatibility testing will be performed when a patient sample is available

Question 2

How would autoantibodies affect compatibility testing?

Answer 2

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

Question 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?

Answer 3

High-frequency alloantibody or a mixture of alloantibodies

Question 4

What does a minor crossmatch consist of?

Answer 4

Recipient RBCs and donor plasma

Question 5

Can crossmatching be performed on October 14 using a patient sample drawn on October 12?

Answer 5

Yes, a new sample would not be needed

Question 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?

Answer 6

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

Question 7

What ABO types may donate to any other ABO type?

Answer 7

O negative

Question 8

What type(s) of RBC(s) is (are) acceptable to transfuse to an O-negative patient?

Answer 8

O negative

Question 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?

Answer 9

Discard the unit

Question 10

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

Answer 10

Compatibility testing would not be affected

Question 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

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

Question 12

A patient showed positive results with screening cells and 4 donor units. The patient autocontrol was negative. What is the most likely antibody?

Answer 12

Anti-k

Question 13

Screening cells and major crossmatch are positive on IS only, and the autocontrol is negative. Identify the problem.

Answer 13

Cold alloantibody

Question 14

Six units are crossmatched. Five units are compatible, one unit is incompatible, and the recipient’s antibody screen is negative. Identify the problem:

Answer 14

Donor unit may have a positive DAT

Question 15

An incompatible donor unit is found to have a positive result on DAT. What should be done with the donor unit?

Answer 15

Discard the unit

Question 16

Screening cells, major crossmatch, and patient autocontrol are positive in all phases. Identify the problem.

Answer 16

Abnormal protein or nonspecific autoantibody

Question 17

A panel study has revealed the presence of patient alloantibodies. What is the first step in a major crossmatch?

Answer 17

Antigen type patient cells and any donor cells to be crossmatched

Question 18

What is the disposition of a donor RBC unit that contains an antibody?

Answer 18

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

Question 19

Given a situation where screening cells, major crossmatch, autocontrol, and DAT (anti- IgG) are all positive, what procedure should be performed next?

Answer 19

Elution followed by a cell panel on the eluate

Question 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.

Answer 20

Cold alloantibody

Question 21

What corrective action should be taken when rouleaux causes positive test results?

Answer 21

Perform a saline replacement technique

Question 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

Identification of antibodies causing a positive DAT

Question 23

How long must a recipient sample be kept in the blood bank after compatibility testing?

Answer 23

7 days

Question 24

What is the crossmatching protocol for platelets and/or plasma?

Answer 24

No testing is required

Question 25

What are the compatibility requirements for an autologous unit?

Answer 25

ABO and Rh typing

Question 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-positive units

Question 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

ABO, Rh, antibody screen, IS crossmatch

Question 28

When may IS crossmatching be performed?

Answer 28

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