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Terms in this set (32)
What patient identification information is needed on the transfusion request?
name, first and last, and unique ID number
What causes the most hemolytic transfusion reactions?
a clerical error - incorrect identification of the patient
How should the sample for pretransfusion be labeled?
Tube should have two unique identifiers - name and unique number, and the date of collection. There must be some mechanism for identifying the phlebotomist.
Why would blood bankers prefer that the samples not be hemolyzed or lipemic?
If the specimen is already hemolyzed, you will not be able to tell if you have a hemolytic antibody. If the specimen is lipemic, it is harder to read the reactions.
How old can the sample be for use in crossmatching?
The sample must be drawn within 3 days if transfusion or pregnancy history is unknown. However, if the patient has not been transfused or pregnant within the last 3 months, the 3 day limit does not apply. To avoid confusion, most hospitals use the 3 day for everyone and only make rare exceptions.
The patient was transfused on 6/21. It appears that the patient is having a DHTR on 6/29. Are you required to still have the patient's sample in the blood bank?
No. The blood bank is only required to have the sample for 7 days after transfusion for just this case scenario. But 9/29 is over 7 days so the sample may have been discarded. Practically speaking, however, they might still have it. The sample itself is good for 3 days. Since the patient could be transfused at any time within that 3 days, so most BB keep the sample a minimum of 10 days, the 3 days the sample is good for and the 7 days after transfusion assuming they were transfused on day 3. That way all samples are treated the same.
What are the serological tests performed in compatibility testing?
ABO/Rh, antibody screen and crossmatch.
If the antibody screen is positive for an IgG antibody, what kind of blood must you give the patient?
If the antibody is an IgG reacting at 37C or AHG, you must give antigen negative units.
The patient records check on Amanda Smith show that in 1985 an anti-Fya was detected in her serum. Today her antibody screen is negative. Do you have to find Fya negative cells for transfusion or can you give her crossmatch compatible units?
Anytime a patient has a clinically significant antibody, you must find antigen negative units for transfusion even if the antibody screen is negative today. The patient has memory cells that can reactivate, start forming the antibody again (anamnestic response), and cause a DHTR.
Why do you have to check previous records when you are performing a crossmatch procedure?
For the safety of the patient. The ABO and Rh must be the same as previously determined. If there is a history of a clinically significant antibody, antigen negative units must be given, even if the current sample is negative.
What are the most important things a crossmatch can do for patient safety?
Verify ABO compatibility and detect clinically significant antibodies.
What problems/antibody class can be detected in IS of the crossmatch?
ABO errors; IgM antibodies; hemolysis
How does the AHG crossmatch differ from the routine, immediate crossmatch?
The abbreviated crossmatch consists only of the IS phase of testing. The AHG crossmatch consists of at least the AHG phase. With the AHG crossmatch, the IS may or may not be performed and the 37C may or may not be read. You would still have to incubate at 37C before you wash and perform the AHG.
When can you perform an abbreviated crossmatch?
Only when there are no current or history of clinically significant antibodies. The abbreviated crossmatch depends on a properly performed, negative antibody screen.
What is the computer crossmatch?
If validated by the specific criteria required by accrediating agencies and the FDA, and there is no history of current or previous clinically significant antibodies, the ABO can be checked by the scanning in the barcode for the computer to confirm the ABO and the unit can be issued
How do you get cells from the donor bag for crossmatch without entering the unit?
Each unit of blood has tubing left on it that originally was used to connect the needle to the bag. Once the needle is removed the tubing is "stripped" so that all the blood goes into the bag. The tube is released and the anticoagulated blood goes back into the line. This is then sealed at specific points making "segments" of blood that can be used for the crossmatch. That way the unit does not have to be entered causing a 24 hour outdate.
Which of the following will pretransfusion testing (including the crossmatch) do?
Ensure that the unit of red cells crossmatched for Jeff Jones went to Jeff Jones and not Jeff Smith (verify donor cells are ABO compatible w/recipient), let you know that you have crossmatch ABO identical or compatible donors, detect the anti-K in the patients serum (detect most of the common encountered clinically significant abs in recipient's serum).
Which of the following will pretransfusion testing (including the crossmatch) WILL NOT do?
Detect that an O unit was crossmatched accidentally for an A patient, detect that an Rh negative unit of red cells was accidentally crossmatched for an Rh positive patient with a negative antibody screen, always detect an antibody to a low incidence antigen that the patient has, prevent primary immunization to rbc antigens, prevent disease transmission, prevent DHTR, and detect the low titer anti-Jka in the patients serum.
If the patient has a positive antibody screen and incompatible crossmatches at AHG, what does this probably mean?
The patient has at least one IgG alloantibody that is reacting with antigen(s) on the screen cells and the donor units.
If the patient has a negative antibody screen with incompatible crossmatches at immediate spin, what does this mean?
If the reactions are fairly weak, it could be a cold alloantibody such as anti-Lea, -Leb, -P1, - M, or -A1 (in an A2 person). The reaction could be strong but they will be matched by the antibody screen. If an incorrect ABO unit was crossmatched, or you're using a sample from a different person with a different ABO (you mixed up samples), or the unit was incorrectly labeled - ABO incompatibilities are usually 4+ reactions. This 4+ reaction will be at IS and carry through the 37C and AHG.
A patient had a negative antibody screen and was crossmatched with 4 units of blood. One of the crossmatch units was incompatible at AHG. What are some of the reasons for this?
The donor unit has a positive DAT;or the antibody is showing dosage with the incompatible crossmatch being homozygous and the compatible one being heterozygous;
or the patient has a low incidence antibody not on the screen cells but positive on the donor cells
Which of the reasons sounds more logical if you realize that the incompatible unit has been crossmatched on 5 other patients and was incompatible with all 5 patients?
The donor unit has a positive DAT. This is the most common reason for this scenario.
If the patient has a positive antibody screen, incompatible crossmatch, and a positive autocontrol, list reasons for these results.
The patient could be having a transfusion reaction with alloantibody attaching to donor cells (the coated donor cells are causing the positive AC);
or could have passively acquired an alloantibody from another component (usually platelets) that is reacting with patient's own cells;
or it could be a cold or warm autoantibody;
or it could be rouleaux (only at IS and 37C - the excess protein is washed off at AHG)
23. For which blood components can you ignore the ABO of the units? Consider cryo, RBC, plasma and platelets.
CRYO - since there are no red cells (any red cells would be lysed) and little to no plasma, the ABO is ignored for the most part, and Platelets, - since they are sometimes hard to come by, the ABO is frequently ignored and "what you get, is what we've got" even though the plasma volume is high. - It may cause a positive DAT due to passive transfusion of incompatible ABO antibodies.
An automobile accident patient came into the emergency room and needed blood. 4 units were issued on emergency release. The BB asked for a sample to test. The nurse came for 6 more units of O neg blood and still no sample. Finally a sample was received after the 10 units were transfused. The patient from previous records was an A+. What do you think the ABO/Rh would look like and why?
The patient sample will be mostly O cells since transfusion of 10 units is generally considered one blood volume. So there would only be a few A cells to react with the anti-A and the anti-D. You would get a certain amount of anti-A, anti-B, and anti-A,B along with the O units to react with the A1 and B cells. The B should still be strong because of the patient's own residual expected anti-B. The reaction strengths will depend on the antibody titers.
Your patient had a negative antibody screen and compatible crossmatches. But three days later had a hemolytic episode. What is the possible cause?
The patient probably had an anamnestic response probably due to a Kidd antibody for it to occur that fast and be hemolytic. The titer was probably too low to detect on the original antibody screen and crossmatch. However, if IgG AHG was used, the Kidd antibody could have been missed. Frequently Kidd antibodies need complement to be detected and IgG AHG lacks the anti-complement component which would have detected the antibody.
If an A + patient has multiple myeloma, how is this going to affect the ABO/Rh, antibody screen and crossmatches?
Multiple myeloma can cause rouleaux. Any reactions that could be expected to be negative at IS or 37C will probably be positive. ABO backtype with the anti-A will be positive (an IS reaction), the IS and 37C of the antibody screen, the screening cells, and crossmatches will probably be positive before AHG. After the washing, the rouleaux will disappear.
25. When can you start giving a multiple myeloma group A cells again?
When there is no longer any passively transfused anti-A or anti-A,B. The patient obviously has passive anti-A and anti-A,B since the antibody titer level is high enough to see it at IS in the backtype. But, once the backtype is normal again, you still must crossmatch the A units through to AHG to make sure there is no anti-A or -A,B to react with those cells at AHG.
A patient has anti-c (80% positive) and anti-Jka (75% positive). What percentage of units screened would be compatible?
If you needed 4 units for the patient that has anti-c (80% positive) and anti-Jka (75% positive), how many units would you have to screen?
What problems/antibody class can be detected in 37C of the crossmatch?
hemolysis; clinically significant IgG alloantibodies, usually in the Rh system
What problems/antibody class can be detected in AHG of the crossmatch?
clinically significant IgG alloantibodies; positive DAT on the donor cells; hemolysis is demonstrated with decreased RBC button size
THIS SET IS OFTEN IN FOLDERS WITH...
Positive DAT and Immune Destruction
Detection of Unexpected Blood Group Antibodies
Donor and Blood Collection
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