Compatibility Testing Flashcards by Kyra Catedral

is composed of serologic
procedures designed to ensure the safety of transfusion.

Compatibility testing

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Compatibility testing

▪ The procedures included are:

▪ ABO and Rh typing

▪ Antibody screening and detection

▪ Crossmatching

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▪ Prevent life-threatening uncomfortable transfusion reactions

▪ Maximize in vivo survival of
transfused red cells.

Crossmatching

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The_______ serves as a double check of ABO errors caused by patient misidentification or donor
unit mislabeling.

crossmatch

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▪ If the recipient possesses a clinically significant_______or a history of one, the crossmatch provides a second means of antibody detection and
checks the results of the antibody screen.

antibody

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The_______ develop the standards for blood banking

AABB and FDA

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▪ According to the AABB Standards:

▪ The crossmatch “shall use methods that demonstrate____ incompatibility and clinically significant____ to red cell antigens and shall include an_____”

ABO

antibodies

antiglobulin phase

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2 types of crossmatch

Major
Minor

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• Not required by AABB since
1976

Minor

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Routinely performed in labs

Major

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Sample used in major crossmatching

Patient serum
Donor RBC

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Sample used in minir crossmatching

Donor serum
Patient Red cells

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What is detected in major crossmatching?

If the patient has antibodies
against donor red cells

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What is detected in minor crossmatching?

• If the donor has antibodies
against the patient’s red cells

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Phases if crossmatching

IMMEDIATE SPIN PHASE (Room temperature (RT), Saline phase)

37C PHASE (Thermophase)

ANTIHUMAN GLOBULIN PHASE (IAT)

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IMMEDIATE SPIN PHASE
Room temperature (RT), Saline phase

Detects???

IgM (cold reacting antibodies)

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37oC PHASE
Thermophase

Detects???

IgM and IgG with wide thermal ranges

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ANTIHUMAN GLOBULIN PHASE
IAT

Detects???

IgG antibodies

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Optimal Phase of Reactivity for Some Common Alloantibodies

Immediate Spin ( Room Temp)

Le^a, Le^b
M, N
Lu^a
P1

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Optimal Phase of Reactivity for Some Common Alloantibodies

37°C Incubation

Potent cold (IgM) antibodies (especially those causing hemolysis)

Some warm antibodies, if high in titer (e.g., D, E, and K)

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Optimal Phase of Reactivity for Some Common Alloantibodies

Antiglobulin Phase

Rh antibodies
Kell
Duffy
Kidd
S,s
Lu^b

It will

Verify donor cell ABO compatibility

Detect most antibodies against donor cells

Crossmatching

Crossmatching will NOT

• Guarantee normal survival of RBCs • Prevent patient from developing an antibody
• Detect all antibodies
• Prevent delayed transfusion
reactions
• Detect ABO/Rh errors

ABO/D phenotype determined
No alloantibodies detected

• No further testing needed

• Perform immediate-spin or computer crossmatch if units are ordered

ABO/D phenotype determined ***Alloantibody detected***

• Identify antibody • Perform a ***complete crossmatch (immediate-spin and antiglobulin)*** on units that are antigen-negative for ***antibody***

ABO/D phenotype determined ***Record of previous alloantibody***

• Rule out or identify additional antibodies • Perform ***immediate-spin and antiglobulin cross-match on units that are antigen-negative*** for ***prior and new alloantibody***

• No further testing needed • Perform immediate-spin or computer crossmatch if units are ordered

No alloantibodies detected

• Identify antibody • Perform a ***complete crossmatch (immediate-spin and antiglobulin)*** on units that are antigen-negative for ***antibody***

Alloantibody detected

• Rule out or identify additional antibodies • Perform ***immediate-spin and antiglobulin cross-match on units that are antigen-negative*** for ***prior and new alloantibody***

Record of previous alloantibody

Major Crossmatch Sample Preparation:

✔ Separate the patient’s plasma and transfer it into a new tube labeled as: • “Patient’s surname – PP” (e.g., Catapang – PP) ✔ Wash donor’s red cells thrice with NSS (Normal Saline Solution) ✔ Prepare a 2–5% donor red cell suspension and label it as: • “Donor’s surname – DR” (e.g., Lim – DR)

Minor Crossmatch Sample Preparation:

✔ Separate the donor’s plasma and transfer it into a new tube labeled as: • “Donor’s surname – DP” (e.g., Lim – DP) ✔ Wash patient’s red cells thrice with NSS ✔ Prepare a 2–5% patient red cell suspension and label it as: • “Patient’s surname – PR” (e.g., Catapang – PR)

• Before crossmatching, determine the________ of both patient and donor. • Grade agglutination and record results.

ABO and Rh blood type

• If ABO & Rh typing results are compatible, proceed to____.

crossmatching

Crossmatching involves three phases:

1. Immediate Spin Phase (IS) – Detects IgM antibodies 2. Thermophase (37°C Incubation) – Detects IgM and IgG antibodies 3. Antihuman Globulin (AHG) Phase – Detects IgG antibodies

PHASE 1: IMMEDIATE SPIN CROSSMATCH • Performed at_____ • Detects_____ that react at cold temperatures

room temperature (RT) IgM antibodies

PHASE 1: IMMEDIATE SPIN CROSSMATCH Major Crossmatch: 1. Prepare a test tube labeled as “____” 2. Add 2 drops of_____ + 1 drop of _____ 3. Mix well and centrifuge for 15 seconds at____ 4. Gently dislodge the red cell button and observe for agglutination 5. Record the results

Major Crossmatch patient plasma (PP); donor RBC suspension (DR) 3,400 rpm

PHASE 1: IMMEDIATE SPIN CROSSMATCH Minor Crossmatch: 1. Prepare a test tube labeled as “_____” 2. Add 2 drops of_____ + 1 drop of______ 3. Mix well and centrifuge for 15 seconds at____ 4. Gently dislodge the red cell button and observe for agglutination 5. Record the results

Minor Crossmatch donor plasma (DP); patient RBC suspension (PR) 3,400 rpm

PHASE 1: IMMEDIATE SPIN CROSSMATCH IF NO AGGLUTINATION IS OBSERVED → Proceed to the…

37°C Thermophase

PHASE 2: 37°C THERMOPHASE (INCUBATION PHASE) Detects…

Detects IgM and IgG antibodies that react at body temperature

PHASE 2: 37°C THERMOPHASE (INCUBATION PHASE) 1. Add 2 drops of_________ or_______ 2. _______ for ______ 3. Centrifuge for 15 seconds at 3,400 rpm. 4. Examine for agglutination and record results.

Low Ionic Strength Solution (LISS) or albumin to both tubes. Incubate the tubes in a 37°C water bath; for 10 minutes

PHASE 2: 37°C THERMOPHASE (INCUBATION PHASE) IF NO AGGLUTINATION IS OBSERVED → Proceed to the_____

AHG Phase

PHASE 3: ANTIGLOBULIN (AHG) PHASE (IAT) Detects…

Detects IgG antibodies that may cause delayed hemolytic transfusion reactions

PHASE 3: ANTIGLOBULIN (AHG) PHASE (IAT) 1. Wash the tubes three times with____ to remove unbound antibodies. 2. Decant the____ completely after the final wash. 3. Add 2 drops of_____ into each tube. 4. Centrifuge for 15 seconds at 3,400 rpm. 5. Gently dislodge the red cell button and observe for agglutination. 6. If no agglutination is observed, add one drop of _____cells, mix, and centrifuge again.

NSS supernatant AHG (Coombs reagent) Coombs’ control

PHASE 3: ANTIGLOBULIN (AHG) PHASE (IAT) • Agglutination after adding Coombs’ cells →

AHG reagent is working properly

PHASE 3: ANTIGLOBULIN (AHG) PHASE (IAT) • No agglutination after adding Coombs’ cells →

AHG test is invalid and must be repeated

STEP 4: INTERPRETATION OF RESULTS • Compatible:_____ → Blood is safe for transfusion. • Incompatible:_____ → Blood is not safe for transfusion.

No agglutination Presence of agglutination

Major Crossmatch Minor Crossmatch Interpretation 0 0

Compatible - Safe for transfusion

Major Crossmatch Minor Crossmatch Interpretation + 0

Incompatible - Recipient has antibodies against donor RBCs

Major Crossmatch Minor Crossmatch Interpretation 0 +

Incompatible - Donor has antibodies against recipient RBCs

Major Crossmatch Minor Crossmatch Interpretation + +

Incompatible - Both donor and recipient have antibodies against each other’s RBCs