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Flashcards in Pretransfusion procedures Deck (52)
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1

proper labeling of of blood from recipients

labels:

  • labeled at bedside with 2 unique identifiers
  • date and time of collection
  • identity of phlebotomist
  • paperwork and blood specimen must match
    • in case of discrepancy or doubt, a new specimen must be obtained

2

If recipient has been pregnant or transfused within 3 months or if history is uncertain, what testing must be done?

What should be done in the absence of the above conditions?

  • sample for pretransfusion testing must be obtained within 3 days of transfusion (day 0 is the date of sample collection) in recently pregnant/transfused patient
  • In the absence of pregnancy or recent transfusion, ABO samples older than 3 days may be used
    • ABO testing, Rh testing, and antibody screening must be performed and no discrepancies or alloantibodies must be detected to use this sample for crossmatching prior to elective surgery
    • do not need to test for weak D
    • anti A reagent is blue
    • anti B reagent is yellow
  • The recipient pretransfusion blood sample as well as the tube segment from any transfused blood must be retained for 7 days after transfusion

3

Visual inspection of donor unit

  • bacterial contamination may appear as purple color, zone of hemolysis, or with clots
  • lipemic units should not be used

4

Causes of forward/reverse typing discrepancies

  • extremes of age 
  • acquired immunodeficiency affecting Ig production (hematolymphoid neoplasms and immunosuppressive agents)

5

Antibody screen

  • done on recipient blood
  • uses 2-4 reagent O test cells that have differential expression of antigens
  • required that 18 clinically significant antigens are represented
  • patient plasma/serum is added to the test cells followed by 
    • immediate spin
    • 37 degree incubation
    • addition of anti human globulin (AHG)
  • room temperature incubation is omitted by many labs since it detects clinically insignificant alloantibodies mostly (anti M, N, Lewis, I, and P)
  • tests may be performed with LISS or PEG
  • if no reactions occur, cross match can proceed
  • if any cells react in screen, then antibody panel is required

6

antibody panel

  • 10-14 different donor test cells, all group O
  • autocontrol run in parallel (recipient serum/plasma added to recipient red cells)

7

Crossmatch

  • Immediate spin or computer crossmatch 
  • Computer crossmatch is ok in patients with negative antibody screen
    • computer system must be validated
    • 2 separate determinations of recipient's ABO/Rh required
  • The IS crossmatch
    • performed at room temperature
    • recipient serum/plasma mixed with donor RBCs followed by centrifugation
    • If known clinically sig alloAb present, then complete or full crossmatch with AHG phase testing is required
    • if cold reacting antibodies are present, the crossmatch may be prewarmed to prevent interference
  • Infant blood up to 4 months old need not be crossmatached if no maternal antibodies are detected
    • the ABO/Rh is determined as for adult recipients, but must only be done once and may be omitted for the remainder of the hospitalization unless lasting beyond 4 months of age or infant leaves and is readmitted
  • If alloantibody is present, the crossmatch must be carried through the antiglobulin phase

8

Compatibility of granulocytes

Must be ABO compatible with recipient serum and must be subjected to crossmatch

 

9

Compatibility of RBCs

Whole blood must be ABO identical

  • If recipient is < 4 months old
    • first choice is O with matching Rh
    • second choice is O with opposite Rh
    • third choice is identical to patient's blood type
    • all RBCs are CMV negative and irradiated

10

Compatibility of platelets and cryo

  • Contain plasma
  • May be transfused outside of ABO compatibility unless unit is visibly bloody
  • preferably, plasma in these products is compatible with recipient red cells
  • preferable that Rh- recipient receive Rh- platelets
    • if giving Rh+ is unavoidable, Rh immune globulin should be suggested
  • first choice is identical to patient type
  • second choice is identical ABO and opposite Rh group
  • Third choice is AB for A or B type patient or AB, A, or B for O type patient

11

Plasma compatibility

  • Must be compatible with recipient's RBCs
  • If recipient < 4 months of age:
    • first choice is AB
    • second choice is A or B or O 
    • Rh should match the patient

 

12

Platelet compatibility for < 4 month old

  • First choice = AB and matching Rh
  • Second choice = match patient's blood type
  • All platelets CMV negative and irradiated

13

Blood transfusion set

  • 170 um filter
  • "microaggregate" 40 um filters are not required
  • same filter can be reused for multiple transfusions for up to 4 hours
  • these filters are not capable of leukoreduction
  • if a leukocyte reduction filter is used, the inline filter may be omitted
  • neonatal tranfusions may be filtered by the blood bank staff prior to release
  • other fluids should not be run in the same line as the unit
    • only normal saline and other FDA approved crystalloids can be run in the same line
    • lactated ringers may cause blood clotting
    • dextrose and hypotonic solutions (0.45%) saline may cause hemolysis

14

Timing of transfusion and monitoring

  • Transfusion must be started within 30 minutes of issue and must be completed within 4 hours
    • if 2 units are released simultaneously then both must be infused within 4 hours
  • Monitoring
    • baseline set of vitals should be recorded
    • observe patient for first 15 minutes
    • slow rate of infusion (2 ml/minute) is good at the beginning
    • a second set of vitals at 15 minutes
    • final set of vitals at end of transfusion
    • recipient should be observed periodically throughout transfusion and for an appropriate length of time thereafter
    • unless there are difficulties, most single unit red cell transfusions can be completed within 90 minutes (and must be completed within 4 hours)

15

In an antibody panel the 10-14 cells must express what antigens?

  1. D
  2. C
  3. E
  4. c
  5. e
  6. M
  7. N
  8. S
  9. s
  10. Pl
  11. Lea
  12. Leb
  13. K
  14. k
  15. Fya
  16. Fyb
  17. Jka
  18. Jkb

16

Phases of antibody panel testing

  1. immediate spin phase
    • antibodies only reacting at this phase are "cold reacting"
    • usually IgM and are likely to be clinically insignificant; may be significant if high titer present (>1,000)
  2. Serum/plasma mixed with RBCs and centrifuged at 37 degrees
    • "warm reacting" antibodies detected
    • usually IgG and potentially clinically significant
  3. Serum/plasma mixed with RBCs in the presence of AHG in the AHG phase (indirect agglutination test - IAT)
    • IgG 
    • likely to be clinically significant

17

Positive reactions on antibody panel

  • agglutination is characterized by red cell clumps
    • graded m+ to 4+
  • hemolysis shows as a pink supernatant

18

Dosage effect seen with which antigens

  1. Kidd
  2. Duffy
  3. Rh
  4. MNS

19

Alloantibodies that are nearly always insignificant

  1. Lewis
  2. Lutheran
  3. I

20

Alloantibodies that are nearly always significant

  1. Kell
  2. Kidd
  3. Rh
  4. Duffy

21

Number of cells required to establish presence of a specific antibody in clinical practice

  • 3 positive cells with reactivity
  • 1 negative cell with nonreactivity

22

Direct antiglobulin test

  1. Polyspecific
    • polyspecific reagent agglutinates RBC coated with IgG or C3
  2. Anti IgG AHG
    • agglutinates red cells with bound IgG on their surface
      • autoantibody bound in vivo to the patient's red cells
      • alloantibody to transfused red cells (usually mixed field)
      • maternal antibody bound to neonatal red cells
      • medications
  3. Anti C3
    • agglutinates red cells with bound C3 on their surface
      • could be positive along with IgG or an IgM

23

Antibodies to high incidence antigens or hight titer, low avidity (HTLA) antibodies

  • Suspected when there is weak reactivity in AHG phase to all cells in the panel
  • Continue to react at high dilutions (>1:64)
  • they can mask other antibodies
  • Clinically significant HTLA antibodies:
    • cartwright (Yta)
    • Holley (Hy)
    • Gregory (Gy)
  • HTLA antibodies that are not significant
    • Chido/Rodgers (Ch/Rg)
    • Sda
    • Csa
    • Kna
    • York (Yka)

24

Antibodies to test reagents

  • autocontrol is negative and there is across the board reactivity
  • test cells can be washed to remove these substances
  • occurs most frequently with gel and solid phase systems
    • in the tube method, the panreactivity may disappear
      • when lot numbers of reagent are used, may also disappear

25

Antibodies to low incidence antigens

  • Wra and Kpa
    • suspected when 1 test cell is reactive within a panel
    • typically these antigens are not indicated on the panel, but the package insert for the test cells delineates a longer list of antigens for which the cell is positive

26

Polyagglutination

- what is it caused by?

- consequences?

  • adult plasma contains naturally occuring IgM antibodies to T, Tn, Tk, and Cad
  • these are normally cryptic antigens that are expressed only when bacterial neuraminidase enzymatically alter red cell antigens (T activation)
  • In adults this phenomenon is mainly a factor in pretransfusion testing
  • In babies this phenomenon is significant in 2 instances:
    • necrotizing enterocolitis (NEC)
      • T activation occurs in up to 25%
      • caused by Clostridia neuramindase
    • Atypical hemolytic uremic syndrome
      • neuraminidase of S pneumoniae
  • Babies with T activation can develop intravascular hemolysis when transfused
    • such babies should receive RBCs with minimal plasma or washed RBCs to minimize the amount of naturally occurring anti T antibodies made in the adult blood
  • The effects of this are transient and abate following resolution of infection

27

Polyagglutination testing

  • lectin Arachis hypogaea can detect T activation
  • polyagglutinable red cells are agglutinated by adult but not cord serum

28

Elution

  • removal of antibody bound to red cells
  • several tenchniques
    • freeze thaw
    • heat
    • acid
    • digitonin
  • the eluate, which contains the Ab, can then be tested against a panel of RBCs to determine its specificity

29

Autoadsorption

  • useful when there are autoantibodies potentialy masking alloantibodies
  • autoantibody is adsorbed using the patient's own red cells that have been pretreated with ZZAP to remove bound autoantibody
  • the adsorbed plasma/serum is left with any alloantibodies that were present and can then be tested against a panel of red cells
  • autoadsorption cannot be used if
    • the patient has been transfused or pregnant in the past 3 months because they may have leftover donor or fetal cells present

30

Alloadsorption

this can be used to remove antibodies from serum in patients who have been transfused or pregnant within 3 months