Question 1

A recipient phenotypes as group O with the following Rh phenotype: D+C+c-E+e+. If this recipient is transfused with red blood cells from six random group O D-positive donors, what Rh alloantibody could this patient produce as a result of transfusion?

Accepted Answer

Although Rh phenotyping is not routinely performed, exposure to the c antigen may cause the recipient to make anti-c because the recipient is negative for the antigen.

Question 2

Which of the following tests is not included in routine compatibility testing?

Accepted Answer

The direct antiglobulin test is not required as part of the compatibility test.

Question 3

What are the two components of the major crossmatch?

Accepted Answer

Donor serum and patient red cells are tested for reactivity.

Question 4

Which of the following blood products requires a crossmatch to be performed before issuing?

Accepted Answer

Granulocytes may contain a significant amount of red blood cells because they are obtained from the "buffy coat" layer during apheresis. These units would require crossmatching before release.

Question 5

If the recipient was transfused within the last 3 months, how long from the time of collection can a sample be used for the crossmatch?

Accepted Answer

The sample can be used for 72 hours if additional crossmatches are required.

Question 6

How long following transfusion must the recipient sample be stored?

Accepted Answer

The recipient's sample should be stored at 1F1F1F1S1F1F1F10 to 6F1F1F1S1F1F1F10 C for 7 days in case there is a transfusion reaction that requires investigation.

Question 7

Antibody screening of the recipient is performed as a component of compatibility testing to detect:

Accepted Answer

The antibody screen detects alloantibodies that the recipient made to red cell exposure from pregnancy or prior transfusions.

Question 8

An antibody screen on a patient with a prior history of transfusion was negative. The crossmatch, performed at immediate spin and antihuman globulin, was incompatible with 1 unit selected. The next step in the investigation would be to:

Accepted Answer

The most likely reason for the incompatibility is that the blood unit has a positive direct antiglobulin test or the patient has developed an antibody to a low-frequency antibody. If the direct antiglobulin test is negative, testing the patient's serum against a selected cell panel of low-frequency antigen positive cells should be performed.

Question 9

An infant less than 4 months old requires which procedures for compatibility testing?

Accepted Answer

An infant less than 4 months old does not make red cell antibodies and therefore does not need to be checked with each transfusion. Initial screens detect antibodies made by the mother.

Question 10

Patient M.M. was admitted to the hospital with acute bleeding. Anti-E was detected in the patient's serum. Four E-negative units of blood were crossmatched for the patient. The units were compatible at immediate spin and following the antiglobulin test. After the antiglobulin test was performed, IgG sensitized red cells gave a 2+ agglutination reaction. The proper interpretation of this 2+ agglutination reaction is the:

Accepted Answer

IgG-sensitized red cells should be positive if adequate washing was performed and antihuman globulin reagent was added.

Question 11

Antibodies detected in the immediate spin crossmatch are usually of which of the following immunoglobulin classes?

Accepted Answer

Immediate spin reactions are typically due to antibodies of the IgM class.

Question 12

When group O blood is not available for transfusion, what is the next alternative?

Accepted Answer

Group O individual has both anti-A and anti-B present in serum, which is incompatible with all blood groups other than group O.

Question 13

The immediate spin or abbreviated crossmatch is an acceptable procedure if the recipient:

Accepted Answer

An immediate spin checks the ABO incompatibility only. It must only be used if no clinically significant antibodies are detected.

Question 14

Select the correct statement regarding the collection of a blood sample for compatibility testing.

Accepted Answer

Samples must be labeled by the bedside following examination of the wristband and correctly identifying the patient. Identification of the phlebotomist and a unique ID number that does not change are also required.

Question 15

Compatibility procedures will address all of the following except to:

Accepted Answer

The compatibility test may prevent the formation of anti-D, but all other antigens are not matched.

Question 16

For autologous units transfused within the collection facility, which part of the compatibility procedure is not required?

Accepted Answer

Autologous units are given to the donor and do not require an antibody screen unless nonautologous units are also to be transfused.

Question 17

If an emergency exists and there is not enough time to perform a crossmatch for red cells, what is the correct procedure?

Accepted Answer

Group O D-negative red blood cell units should be released and the crossmatch procedure completed as soon as possible.

Question 18

Your blood bank mistakenly transfused 1 unit of D-positive red blood cells to a patient who was typed as D-negative. The patient had no history of a previous transfusion or pregnancy. Antibody detection testing was negative in pretransfusion testing. The crossmatch in this case was:

Accepted Answer

The abbreviated or full crossmatch would not have detected this error because anti-D had not been formed and the unit would have been compatible.

Question 19

A group O patient was crossmatched with group B red blood cells. What phase of the crossmatch will first detect this incompatibility?

Accepted Answer

ABO incompatibilities should be detected on immediate spin.

Question 20

Given the following red cell antigen frequencies: 
Which of the following red cell alloantibodies would be responsible for incompatible crossmatches with one 1 of 10 random donor units?

Accepted Answer

Anti-K is incompatible with 1 in 10 units of red blood cells.

Quiz 8: Compatibility Testing