Compatibility Testing Flashcards
is composed of serologic
procedures designed to ensure the safety of transfusion.
Compatibility testing
Compatibility testing
▪ The procedures included are:
▪ ABO and Rh typing
▪ Antibody screening and detection
▪ Crossmatching
▪ Prevent life-threatening uncomfortable transfusion reactions
▪ Maximize in vivo survival of
transfused red cells.
Crossmatching
The_______ serves as a double check of ABO errors caused by patient misidentification or donor
unit mislabeling.
crossmatch
▪ 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
The_______ develop the standards for blood banking
AABB and FDA
▪ 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
2 types of crossmatch
Major
Minor
• Not required by AABB since
1976
Minor
Routinely performed in labs
Major
Sample used in major crossmatching
Patient serum
Donor RBC
Sample used in minir crossmatching
Donor serum
Patient Red cells
What is detected in major crossmatching?
If the patient has antibodies
against donor red cells
What is detected in minor crossmatching?
• If the donor has antibodies
against the patient’s red cells
Phases if crossmatching
IMMEDIATE SPIN PHASE (Room temperature (RT), Saline phase)
37C PHASE (Thermophase)
ANTIHUMAN GLOBULIN PHASE (IAT)
IMMEDIATE SPIN PHASE
Room temperature (RT), Saline phase
Detects???
IgM (cold reacting antibodies)
37oC PHASE
Thermophase
Detects???
IgM and IgG with wide thermal ranges
ANTIHUMAN GLOBULIN PHASE
IAT
Detects???
IgG antibodies
Optimal Phase of Reactivity for Some Common Alloantibodies
Immediate Spin ( Room Temp)
Le^a, Le^b
M, N
Lu^a
P1
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)
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:
- Immediate Spin Phase (IS) – Detects IgM antibodies
- Thermophase (37°C Incubation) – Detects IgM and IgG antibodies
- 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:
- Prepare a test tube labeled as “____”
- Add 2 drops of_____ + 1 drop of _____
- Mix well and centrifuge for 15 seconds at____
- Gently dislodge the red cell button and observe for agglutination
- Record the results
Major Crossmatch
patient plasma (PP); donor RBC suspension (DR)
3,400 rpm
PHASE 1: IMMEDIATE SPIN CROSSMATCH
Minor Crossmatch:
- Prepare a test tube labeled as “_____”
- Add 2 drops of_____ + 1 drop of______
- Mix well and centrifuge for 15 seconds at____
- Gently dislodge the red cell button and observe for agglutination
- 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)
- Add 2 drops of_________ or_______
- _______ for ______
- Centrifuge for 15 seconds at 3,400 rpm.
- 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)
- Wash the tubes three times with____ to remove unbound antibodies.
- Decant the____ completely after the final wash.
- Add 2 drops of_____ into each tube.
- Centrifuge for 15 seconds at 3,400 rpm.
- Gently dislodge the red cell button and observe for agglutination.
- 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
