TM Pretransfusion Testing Flashcards
Define (Major) Crossmatch
- ensures ABO compatibility between donor cells and patient plasma
What happens after a crossmatch ?
- allocation/ tagging:
- to one patient only for 96 hrs
- unit is tagged (first, last, ULI, BBIN) - Issuing; units leaves blood blank
- Transfusion
Pre-transfusion testing criteria
- informed consent
- patient ID, sample collection, labeling
- patient history
- ABO Rh
- antibody screen
- crossmatch
T or F: ABO Rh is done with every single pretransfusion testing
TRUE; ABO Rh is done with every single pretransfusion testing
Requirements for identifying patients for pretransfusion testing …
- two means of identifying = nurse/ barcode reader AND phlebotomist
- unique identifier; ULI/ PHN/ military ID/ RCMP ID
- legal first and last name
What information MUST be on the requisition?
- first and last name
- ULI
- BBIN/TSIN
- time and date
- 2 signatures (nurse/ barcode reader AND collector)
NOTE: patient ID + labelling MUST occur at bedside
Specimen type for pretransfusion
2 EDTA
What info must be on the specimen tube?
- first and last name
- ULI
- BBIN
BBIN
blood bank identification number
TSIN
transfusion service identification number
What must you do if there are any missing info, illegible, or mismatches (letter/number)?
reject specimen and request recollection
- fill out occurrence management form (RLS)
when are full clerical checks performed?
- specimen received in lab (acceptance/ rejection)
- ABO, Rh, Ab screen
- result entry
NOTE: perform constant checks (accession) performed continuously throughout testing
T or F; We check transfusion Hx on each patient with every collection
TRUE
- ABO Rh type
- Ab screen results
-Ab ID/Ag typing
- adverse events (transfusion rxns)
- previous transfusion/ pregnancy
- special instructions/products (irradiated, washed, IgA deficient)
how many ABO Rh tests must be performed to comply with electronic XM?
2
- historical type is OK if performed by testing lab
- ABO Rh is always done on current sample
- any discrepancy must be resolved
- mismatch from historical record must be investigated (repeat patient ID, collection)
what is an antibody screen?
detects significant antibodies
> Rh, Kell, Duffy, Kidd, Ss
Minor crossmatch
- designed to test the DONOR’S SERUM/ PLASMA with the recipient’s red cells
Advantages of a type & screen
- prevents allocation of blood that won’t be needed
- permits more stock to be available
- makes good use of time and resources
- decreases cost
- if blood IS required, electronic XM is quick!
Type & Screen
- patient ID, valid sample
- Hx check
- ABO Rh
- Antibody screen; if no history and Ab screen is neg = STOP
When transfusion needed = electronic XM
How does the procedure for Ab screen differ if there is Hx of clinically significant Abs OR Ab screen is positive ?
- Ab ID, DAT !
- Ag type patient (should be Ag neg)
- Antigen type donors (based on Ag frequency)
- SEROLOGICALLY crossmatch 2 units
How is blood issued in an emergency ?
- if ABO unknown or unresolved discrepancy = issue group O
- if Rh unknown/ discrepant:
issue Rh pos to males > 4 mos and females >45 y/o
issue Rh neg to males ≤ 4 mos and females ≤ 45 y/o
NOTE: all unmatched blood is k neg in EDM zone
limitations of Ab screen
may miss Abs to low frequency antigens not represented on screen cells
limitations of IS crossmatch
Immediate Spin:
- false neg due to weak ABO Ab; important to check ABO typing
- false pos due to cold IgM antibody reacting at RT (allo or auto)
Limitations of serological XM
- weak Ab and dosage (donor cell heterozygous expression of Ag)
- donor Ag neg for corresponding Ab
- screening cells are more sensitive than donor cells
3 general characteristics of Ab screen cells
- O cells
- Representative of general pop’n (R¹R¹, R²R², rr)
- at least 1 cell with homozygous expression of Ag show dosage
CABORh
Confirmatory ABO Rh:
- tested from a different draw time
- if 2 separate ABO Rh already exist, DO NOT DO CABORh
