Pre-transfusion testing

Question 1

List the steps involved in pre-transfusion testing

Answer 1

1. Sample collection: request form; collection; appropriate sample
2. ABO & Rh(D) grouping
3. Ab screen (& ID if required)
4. Select appropriate donor
5. Cross-match
6. Transfusion

Question 2

Explain the importance of the date/time of collection and phlebotomist signature on the sample tube and request form for TS samples

Answer 2

1. Info. required to identify recipients details

2. Must be Signed by person collecting that the sample tube & request form is labelled w/ appropriate identifiers

Question 3

Explain the scenarios where samples for TS testing are valid for 72 hours, and 7 days

Answer 3

1. If patient not transfused or pregnant in past 3 months = sample is valid for 7 days from collection
2. If patient has been transfused or preg. in past 3 months = sample is valid for 72 hours (3 days) from collection [bc inc. risk for amnestic response]

Question 4

Explain why we perform an antibody screen

Answer 4

• to detect clinically sig. Ab that may be present in patient’s plasma
• need to know to avoid haemolysis from giving donor blood that has Ag specific twds recipient’s Ab (avoid HTR or HDNB)

Question 5

how one is an Ab screen performed?

Answer 5

• use Ab screening cell panel
• Patient’s plasma reacted against screening cells from different O doners to detect which Ab patient has w/ the Rh(D) groups & other Ag groups
• IAT @ 37ºC
• Postitve screen: ≥1 positive rxn in any cells (/tests)
• Negative screen: no agglutination rxn in any cells

Question 6

Explain the characteristics of the cells used in an antibody screen

Answer 6

• come from different O donors: not deal w/ A, B, A,B Ag
• Have Ag from Rhesus, Kell, Duffy, Kidd, MNS, Lewis, Lutheran
• Have R1R1 (CDe) & R2R2 (cDE)
  => to detect clinically sig. Ab in patients plasma to any of those Ag

Question 7

You perform an antibody screen; there is no reaction with the three cells and the reactions are validated with AHG control cells. What is your interpretation of these results?

Answer 7

negative screen = patient as no an Ab

Question 8

Explain donor RBC selection in individuals with and without antibodies.

Answer 8

• If possible, donor RBC should match recipient’s ABO & Rh(D) group
• If recipient has a clinically Sig. Ab. give then a cell that NOT express that Ag
• If Ab is present & not clinically sig. can use IAT cross-match compatible cells (ie neg Ab screen for CSig. Ab)

Question 9

Explain when it is appropriate to perform cross-matches by IS and IAT

Answer 9

• IS: ABO compatibility. Only when patient has NEVER had a clinically sig. Ab detected in their plasma (no previous exposure)
• IAT: ABO compatibility & compatibility w/ other blood groups. Use if patients HAS had a Clinically sig. Ab in their plasma (had previous exposure = not want amnestic response)

Question 10

Requirements for ABO grouping

Answer 10

• ABO grouping
• Rh(D) grouping
• Confirm Hx records

Question 11

What is the group and hold?

Answer 11

aka group & screen

• Ab screen & STOP pre-transfusion test
• If patient’s having complications continue w/ crossmatch = have blood ready for patient
• Neg Ab screen & no Hx of CSig. Ab=> IS crossmatch
• Pos Ab screen & have CSig. Ab => Ab ID & IAT crossmatch

Question 12

Name of guidelines AUstralia & New Zealand must follow in their transfusion labs.

Answer 12

ANZSBT guidelines for transfusion & immunohaematology laboratory practice.
ANZSBT: Aus & NZ Society of blood transfusion

Question 13

Requirements for transfusion in emergency

Answer 13

• Provide O Rh(D) neg E neg & K neg blood initially
• Provide group-specific blood ASAP - when done blood group test
• Complete pre-transfusion test ASAP
  • 10 min: ABO Rh(D) group
  • 30 min: Ab screen & cross match (*if Ab screen is neg can do crossmatch w/ IS given patient not have Hx of CSig. Ab, but if pos. -> Ab ID & Xmatch w/ IAT)
• Labelled