Compatibility Testing Flashcards
What is the purpose of pre-transfusion testing?
To select blood components that will not cause harm to the recipient and will have acceptable survival when transfused.
Properly performed compatibility tests confirm ABO compatibility and detect significant unexpected antibodies.
What are the components of compatibility testing?
- Proper specimen collection
- Patient transfusion history review
- ABO, Rh, Antibody Screen
- Crossmatching
- Transfusion
What must be confirmed for proper patient identification?
- Full name
- D.O.B
- Unique hospital number
- Physician
Must confirm patient identification from armband on the patient.
What are the labeling requirements for a specimen?
- Full name
- Unique ID number
- DOB
- Date and time of collection
- Phlebotomist initials
- Physician (not mandatory)
What must be done if a sample is collected more than 72 hours prior to testing?
Complement dependent antibodies may be missed, as complement can become unstable.
What is included in the compatibility testing procedure?
- ABO/Rh
- Antibody screen
- Crossmatch of donor cells with patient plasma
This procedure is essential to prevent immune-mediated hemolytic transfusion reactions.
What is the major crossmatch?
The most important crossmatch comparing donor erythrocytes to recipient serum looking for antibodies in recipient serum against donor erythrocytes.
What does a negative antibody screen indicate in relation to crossmatching?
No clinically significant antibodies are detected in the antibody screen testing.
What does a positive crossmatch indicate?
Incompatibility exists between donor and recipient.
What does the term ‘anamnestic response’ refer to?
The second or subsequent exposure to a specific antigen, resulting in a different response compared to the primary response.
What is the immediate spin crossmatch method?
A procedure that does not require the AHG phase if no clinically significant antibodies are detected in the antibody screen and the patient has no history of antibodies.
What should be done if there is a positive antibody screen?
An AB identification panel should be performed, and antigen negative blood must be crossmatched.
What factors could lead to a positive major crossmatch despite a negative antibody screen?
- Incompatibility due to ABO system
- Patient serum containing ABO antibody
- Patient serum containing passively transferred anti-A or anti-B
What is the significance of reviewing patient transfusion history?
It may reveal previously detected antibodies that could affect compatibility.
What compatibility testing is required for platelets, frozen plasma, and cryoprecipitate?
Compatibility testing is NOT required, but ABO compatibility is required.
What is the procedure for immediate spin crossmatch?
- Label tubes for each donor unit
- Add patient serum/plasma to each tube
- Add washed donor cell suspension
- Centrifuge and observe for agglutination
What must be done if agglutination is observed during crossmatching?
Investigate to rule out room temperature antibody interference, rouleaux formation, wrong patient group, or mislabeled donor unit.
What type of blood may be transfused to Rh Negative individuals in emergencies?
Rh Positive units.
What testing should be performed if cold allo or autoantibody is suspected?
Perform RT antibody screen including autocontrol due to detected incompatibility at RT
Cold antibodies can interfere with crossmatching and must be evaluated.
What is the role of the saline replacement technique?
It is used to rule out the presence of rouleaux due to abnormal protein in plasma
Rouleaux formation can mimic agglutination, particularly in conditions like multiple myeloma.
What is necessary for electronic/computer crossmatching?
Computer crossmatching may be used if:
* The system has the capability of interpreting ABO results
* The system has been validated to prevent release of ABO incompatible products
This reduces the risk of human error in blood transfusion.
What details must the LIS have for electronic crossmatching?
The LIS must include:
* blood donor unit number
* product type
* ABO/Rh
* donor confirmation typing
* interpretation of compatibility with patient
Accurate data entry is crucial for patient safety.
What are the criteria for a patient in electronic crossmatching?
The following criteria must be met:
* The patient must have a Negative antibody screen
* The patient’s ABO type must be determined twice
* A second individual must compare results of previous ABO results on file if available
* The ABO type of the donor must be re-typed by the issuing laboratory
Rigorous verification processes are essential to ensure compatibility.
What are the first and second choice selections for an O recipient?
First choice: O
Second choice: NONE
O blood type is the universal donor, making it the safest choice.
What must be included in the labeling form of blood units?
The labeling form must include:
* patient’s full name
* ID number
* ABO/Rh of patient and unit
* donor #
* compatibility results
* tech ID
Proper labeling is critical to prevent transfusion errors.
What should be visually inspected in blood products?
Inspect for:
* Colour (hemolyzed, jaundiced, abnormal)
* Appearance (clots, particulate matter, leaking units)
* Expiry Date
Visual inspection helps identify potential issues before transfusion.
True or False: The unit visually inspected for abnormalities includes checking for bacterial contamination.
True
Ensuring the safety of blood products is paramount.
What is the time limit for blood out of the refrigerator before it must be returned?
30 minutes
Blood must be stored at a temperature between 1-10°C to ensure safety.
In what situations can Rh Positive blood be released to Rh Negative recipients?
- Rh negative male patient > 18 years without anti-D antibody
- Rh Negative women > 50 years without anti-D antibody
What are common causes of an incompatible crossmatch?
- ABO ERRORS
- ALLOANTIBODY IN RECIPIENT
- AUTOANTIBODY IN PATIENT/RECIPIENT
- POSITIVE DAT IN DONOR
- ROULEAUX
- POLYAGGLUTINABLE DONOR RBC’s
- ALBUMIN-AGGLUTINATING PHENOMENON
- CONTAMINENTS
What is the definition of massive transfusion?
Replacement of one blood volume in 24 hours or 50% of blood volume in less than 3 hours
Alternatively, administering 4-5 units of Packed RBC’s in one hour.
What is the recommended ratio of packed RBC’s, thawed frozen plasma, and platelets in massive transfusion protocols?
1:1:1
This ratio is recommended to restore blood volume and maintain various biochemical parameters.
What treatment is aimed at in cases of acute blood loss?
Replacement of oxygen-carrying capacity of lost fluids
Volume replacement is generally prioritized over RBC replacement.
What are the two categories of synthetic volume expanders?
- CRYSTALLOIDS
- COLLOIDS
What types of crystalloids are commonly used for immediate volume replacement?
- Ringer’s lactate
- Saline
What must be done for blood samples used for testing after transfusion?
Must be stoppered and stored between 1°C and 6°C for 7 to 14 days
This is important for delayed hemolytic reaction testing.
What is required for emergency release of blood?
- SIGNED statement from requesting physician
- Positive identification of patient
- Patient unique identification number
- ABO and Rh of donor units issued
- Segments labeled from emergency released units
- NOTICEABLY labeled units indicating incomplete compatibility testing
What should blood for neonatal transfusion be compatible with?
Maternal AB if present
This ensures safety for infants under 4 months old.
What must be done if clinically significant antibodies are detected in neonatal blood testing?
Transfusion of antigen negative units or compatible units in the AHG phase
What is the maximum age of blood preferred for neonatal transfusion?
Less than 7 days old
Blood must be as fresh as possible for neonatal transfusions to babies under 4 months of age or in utero exchange transfusions.
What type of RBCs should be used if the mother’s antibody screen is negative and the baby’s DAT is negative?
O Negative, CMV Negative, Irradiated RBCs
The unit can be split into 3 portions prior to issuing.
What must be done if the mother has an alloantibody or the baby’s DAT is positive?
Phenotype O Negative units for the antigen to the alloantibody
A full cross match using the mother’s plasma/serum is performed.
What does SAG-M stand for in pediatric transfusions?
Saline, Adenine, Glucose, Mannitol
SAG-M units have a 42-day shelf life.
What is the risk of GVHD in children with impaired immune competence?
Graft versus host disease
Transfusion of irradiated units helps reduce the risk of GVHD.
When are exchange transfusions indicated for neonates?
In severe cases of hemolytic disease of the newborn (HDN)
A two-volume exchange removes approximately 80 to 90% of the infant’s original circulating blood.
What is the minimum Hb level considered anemic for a newborn?
Less than 120 g/L
Full-term newborns typically have elevated Hb levels of 140 to 200 g/L.
What is the purpose of intrauterine transfusions?
To maintain fetal Hb above 100 g/L
Procedures are repeated every 2 to 4 weeks until 34-36 weeks gestation.
What is the only solution compatible with red cell transfusions?
0.85% sodium chloride (saline)
Never transfuse IV medications via transfusion line; only blood can be administered via transfusion IV line.
Which solutions are not compatible with red cells?
Ringer’s lactate and glucose
Ringer’s lactate promotes clotting, glucose causes agglomeration/clumping of red cells.
What should be monitored when using blood warmers?
The temperature of the blood
Red cells are damaged at temperatures above 38°C.
What is the benefit of using electromechanical infusion pumps for blood transfusions?
Offers ability to calculate more accurate flow rate of blood
Routine transfusion speed is set as tolerated by the patient or within 4 hours.
What is autologous transfusion?
Collection of a patient’s own blood for their use only
Patients can donate weekly, up to 4 units prior to surgery.
What happens to unused red cells in autologous transfusion?
They will expire on the shelf and be discarded
The hospital provides written confirmation of final disposition after units expire.
