Blood Bank II Ch 9: Compatibility Testing
Given the following red cell antigen frequencies: K 10% E 30% k 90% P1 80% Which of the following red cell alloantibodies would be responsible for incompatible crossmatches with one 1 of 10 random donor units? - Anti-K - Anti-E - Anti-k - Anti-P1
Anti-K (Anti-K is incompatible with 1 in 10 units of red blood cells)
A recipient is 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? - Anti-E - Anti-C - Anti-c - Anti-D
Anti-c (Although Rh phenotyping is not routinely performed, exposure to the donor c antigen may cause the recipient to make anti-c because the recipient is negative for the antigen)
How long following transfusion must the recipient's sample be stored? - 5 days - 7 days - 10 days - 14 days
7 days (The recipient's sample should be stored at 1° to 6° C for 7 days in case there is a transfusion reaction that requires investigation)
How many units of red blood cells are required to raise the hematocrit of a 70-kg nonbleeding adult man from 24% to 30%? - 1 - 2 - 3 - 4
2 (Each red cell unit should raise the hematocrit by 3%)
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? - 3 days - 5 days - 7 days - 10 days
3 days (The sample can be used for 72 hours if additional crossmatches are required)
Which reactivity phase of the screen would typically detect rouleaux? - 4° C - 15° C - 37° C - Antihuman globulin
37° C (In the screen, 37° C is typically where rouleaux are initially detected)
If an emergency exists and there is not enough time to perform a crossmatch for red cells, what is the correct procedure? - Release group O, D-negative whole blood. - Release group O, D-negative RBC units. - Release group AB fresh frozen plasma until the blood type is performed. - Release ABO-compatible blood based on the patient's prior record in the computer.
Release group O, D-negative RBC units (Group O D-negative red blood cell units should be released and the crossmatch procedure completed as soon as possible)
Select the correct statement regarding the collection of a blood sample for compatibility testing. - The sample must be labeled at the bedside. - The sample requires a new numeric identifier for the patient for each admittance. - The sample may be labeled at any time in an emergency. - The sample does not require a means to identify the phlebotomist.
The sample must be labeled at the bedside (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)
The use of the electronic (computer) crossmatch is restricted to recipients who: - are group O. - do not have a clinically significant antibody. - have had successful transfusions in the past. - have transfusion history that has been documented in the computer.
do not have a clinically significant antibody (The electronic (computer) crossmatch may be performed only on patients who do not have or have a history of a clinically significant antibody)
What is the immunoglobulin class of antibodies detected in the immediate-spin crossmatch? - IgA - IgM - IgG - IgD
IgM (Immediate-spin reactions are typically due to antibodies of the IgM class)
A group O patient was crossmatched with group B red blood cells. What phase of the crossmatch will first detect this incompatibility? - Immediate-spin - 37° C low-ionic strength solution - Indirect antiglobulin - None of them; unit is compatible
Immediate-spin (ABO incompatibilities should be detected on immediate-spin)
When is the immediate-spin or abbreviated crossmatch an acceptable procedure for the recipient? - No prior or existing clinically significant antibodies - Never been pregnant or transfused - Needs blood before a sample can be obtained - Using blood from a directed donation
No prior or existing clinically significant antibodies (An immediate-spin checks the ABO incompatibility only. It must only be used if no clinically significant antibodies are detected)
When type O blood is not available for transfusion for a type O recipient, what is the next alternative? - Group A red blood cells - Group AB red blood cells - Washed group B red blood cells - None
None (Group O individuals have both anti-A and anti-B present in serum, which is incompatible with all blood groups other than group O)
Select the item that cannot be used to perform an antibody screen for an infant less than 4 months old. - Infant serum - Paternal serum - Maternal serum - Infant eluate
Paternal serum (The father's serum is not useful when screening for antibodies in an infant)
An antibody screen on a patient with a prior history of transfusion was negative. The crossmatch was incompatible with 1 unit selected at AHG phase. What is the next step in the investigation? - Perform a prewarm procedure for crossmatching - Perform a direct antiglobulin test on the incompatible unit - Redraw the patient and begin a new crossmatch - Crossmatch a new unit and discard the incompatible unit
Perform a direct antiglobulin test on the incompatible unit (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 antigen. 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)
Select the item that compatibility procedures will not address. - Prevent formation of all red cell antibodies - Prevent life-threatening transfusion reactions - Maximize in vivo survival rate of red cells - Check ABO compatibility
Prevent formation of all red cell antibodies (The compatibility test may prevent the formation of anti-D, but not all other antigens are matched)
A 29-year-old female was admitted to the emergency room with severe bleeding. The blood type was group AB, D-negative. Six units of RBCs are ordered STAT. Of the following types available in the blood bank, which would be the most preferable for crossmatch? - AB, D positive - A, D negative - A, D positive - O, D negative
A, D negative (Transfusion of RBCs to D-negative recipients should be D-negative when possible, especially in the case of females of childbearing age. Group AB recipients can receive AB, A, and B RBCs, as well as group O; group O, especially group O, D-negative blood should be reserved for emergencies when the blood type is not known and for group O, D-negative recipients)
What compatibility testing procedures are required for an infant less than 4 months old? - Antibody screen with each unit released in a 48-hour period - ABO and D typing and antibody screen initially only; units released without additional testing, if the screen is negative - Immediate-spin crossmatch with each unit released - Group O, D-negative units; no testing is necessary
ABO and D typing and antibody screen initially only; units released without additional testing, if the screen is negative (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. Type and screen retesting would have to be performed if neonate is discharged and subsequently readmitted)
What can be done to increase the sensitivity of the antibody screen in a compatibility test? - Extend the incubation time. - Increase the serum-to-cell ratio. - Use an enhancement such as polyethylene glycol. - All of the above are correct.
All of the above are correct (All of the above are correct)
For autologous units transfused within the collection facility, which part of the compatibility procedure is not required? - ABO phenotyping - D phenotyping - Antibody screen - Transfusion history check
Antibody screen (Autologous units are given to the donor and do not require an antibody screen unless nonautologous units are also to be transfused)
A donor unit with a positive DAT would cause reactions at what phase of the crossmatch? - Immediate-spin - Antiglobulin - None; it would be compatible - All phases
Antiglobulin (The antiglobulin phase of the crossmatch would be positive because it would detect donor cells with attached IgG antibodies)
A patient 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. What is the proper interpretation of this 2+-agglutination reaction? - Antihuman globulin washing procedure was adequate. - IgG-sensitized red cells spontaneously agglutinated. - Crossmatch was incompatible. - Patient's anti-E reacted with the IgG-sensitized red cells.
Antihuman globulin washing procedure was adequate (IgG-sensitized red cells (check cells) should be positive if adequate washing was performed and antihuman globulin reagent was added)
Your blood bank mistakenly released a D-positive red blood cell unit that subsequently transfused to a patient who typed as D-negative. The patient had no history of a previous transfusion or pregnancy. Antibody detection testing was negative in pretransfusion testing. Predict the crossmatch result in this case. - Compatible at immediate-spin - Incompatible at immediate-spin only - Not necessary to perform - Incompatible at antihuman globulin only
Compatible at immediate-spin (The AHG phase of the crossmatch would not have detected this error because anti-D had not formed and the unit would have been compatible)
Why is antibody screening of the recipient performed as a component of compatibility testing? - Detects red cell alloantibodies - Detects irregular antigens on the recipient's red cells - Detects human leukocyte antigen antibodies - Detects incompatibilities with the donor's red cells
Detects red cell alloantibodies (The antibody screen detects alloantibodies that the recipient made to red cell exposure from pregnancy or prior transfusions)
Which of the following tests is not included in routine compatibility testing? - ABO phenotyping - Direct antiglobulin test - D typing - Antibody screen
Direct antiglobulin test (The direct antiglobulin test is not required as part of the compatibility test)
What are the two components of the major crossmatch? - Recipient red cells and donor serum - Donor red cells and recipient serum - Reverse ABO cells and recipient serum - Screening cells and donor serum
Donor red cells and recipient serum (Donor red cells and patient serum are tested for reactivity)
Which of the following blood products requires a crossmatch before issuing? - Group AB fresh frozen plasma that is transfused to a group O - Human leukocyte antigen-matched platelets - Cryoprecipitated AHF - Granulocyte concentrates that have more than 2 mL of red blood cells
Granulocyte concentrates that have more than 2 mL of red blood cells (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)
To what does the abbreviation "MSBOS" refer? - Monthly surgical blood order schedule - Minimum surgical blood order staffing - Maximum blood order schedule - Minimum safe blood order schedule
Maximum blood order schedule (The maximum surgical blood order schedule outlines the typical number of blood units that should be set up for various surgical procedures)
A tube was received in the blood bank for crossmatching. The label was torn and the only information that was visible was the patient's last name and the medical record number. Which of the following is an acceptable procedure? - Request a recollection of the specimen. - Call the phlebotomist back to relabel the tube. - Reprint a label using the MRI as the identifier. - Use the tube since the MRI is visible.
Request a recollection of the specimen (Tubes used for crossmatching must have the patient's name, unique number, date and time of collection and phlebotomist identifier at the minimum. Tubes that do not have proper labels should not be used and recollection is necessary)
