5 COMPATIBILITY TESTING Flashcards
(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
B. Compatibility testing will be performed when a patient sample is available
When patient serum is available, it will be crossmatched with donor cells. Patient serum might contain antibodies against antigens on donor cells that may destroy donor cells. If an incompatibility is discovered, the problem will be reported immediately to the patient’s physician.
(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
C. ABO, Rh, antibody screen, and crossmatching may show abnormal results
Autoantibodies may cause positive reactions with screening cells, panel cells, donor cells, and patient cells. The DAT result will be positive; however, DAT is not included in compatibility testing.
(3) An antibody screen is reactive at the IAT phase of testing with all three cells of a threecell 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
B. High-frequency alloantibody or a mixture of alloantibodies
High-frequency alloantibodies or a mixture of alloantibodies may cause all three screening cells to be positive. A negative autocontrol would rule out autoantibodies.
(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
C. Recipient RBCs and donor plasma
A minor crossmatch consists of recipient RBCs and donor serum or plasma.
(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
A. Yes, a new sample would not be needed
Compatibility testing may be performed on a patient sample within 3 days of the scheduled transfusion; however, if the patient is pregnant or was transfused within 3 months, the sample must be less than 3 days old.
(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
B. Check inventory of A-, B-, and O-negative units
An AB person is the universal recipient and may receive any blood type; because only a type and screen were ordered and blood may not be used, check inventory for A-, B-, and O-negative units.
(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
B. O negative
An O-negative individual has no A or B antigens and may donate RBCs to any other ABO type.
(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
B. O negative
An O-negative individual has both anti-A and anti-B and may receive only O-negative
RBCs.
(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
C. Discard the unit
Leaking may indicate a broken seal or a puncture, which indicates possible contamination of the unit, even if the RBCs appear normal. The unit should be discarded.
(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
D. Compatibility testing would not be affected
Compatibility testing would not be affected if the donor has anti-K in his or her serum. This is because the major crossmatch uses recipient serum and not donor serum. Other tests, such as ABO, Rh, and antibody screen on the recipient, also would not be affected.
(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
D. There are concordant results of at least one determination of the recipient’s ABO type on file
ABO determinations must be concordant on at least two occasions, including the current sample.
(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
D. Anti-k
Anti-k (Cellano) is a high-frequency alloantibody that would react with screening cells and most donor units. The negative autocontrol rules out autoantibodies. Anti-H and anti-S are cold antibodies and anti-Kpa is a low-frequency alloantibody.
(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
A. Cold alloantibody
A cold alloantibody would show a reaction with screening cells and donor units only at the IS phase. The negative autocontrol rules out autoantibodies and abnormal protein.
(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
C. Donor unit may have a positive DAT
The incompatible donor unit may have an antibody coating the RBCs, or the patient may have an alloantibody to a low-frequency antigen. An alloantibody to a highfrequency antigen would agglutinate all units and screening cells.
(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
A. Discard the unit
The incompatible unit may have RBCs coated with antibody and/or complement. If RBCs are sensitized, then some problem exists with the donor. Discard the unit.
