CLS 306 - Pretransfusion Testing

Review of Foundations

• ABO & Rh (Blood Type)
• Other Blood Group Systems
• Direct Antiglobulin Test (DAT) & Indirect Antiglobulin Test (IAT) / Antibody Screen (ABS)
  • Antibody Identification (Ab ID Panel)
• These are the foundations for transfusion practices and other medical conditions like Hemolytic Disease of the Newborn & Fetus (HDFN).
• Compatibility Testing: The next subject, venturing further towards transfusion practices.

Purpose of Pretransfusion / Compatibility Testing

• Select the safest blood/blood components for transfusion that:
  • Meets recipient's needs
  • Provides acceptable donor RBC survival rates
  • Eliminates destruction of recipient's cells
  • Weighs potential risks against benefits
• Crossmatch: Fourth of the primary foundations in pretransfusion testing for a safe transfusion.

Process Leading to Compatibility Testing

• Assumption:
  1. Patient had an H&H test performed and the results showed a low H&H.
  2. Patient is anemic to a point where the clinician believes the patient needs a blood transfusion.
  3. Clinical staff must initiate the transfusion on behalf of the patient.

Why Transfuse a Patient?

• To improve the patient's blood oxygen-carrying capacity to appropriately sustain the vital organs.

Oxygen-Carrying Mechanism

• Human Hemoglobin:
  • Oxygen molecules bind to heme within red blood cells.
  • Hemoglobin molecule carries oxygen.

Hemoglobin-Oxygen Dissociation Curve

• Shows the affinity of red cells to oxygen or its ability to release oxygen to the vital organs.
• Left Shift (Decreased P50, increased affinity):
  • Temperature ↓
  • PC02 ↓
  • 2,3-DPG ↓
  • pH ↑
• Right Shift (Increased P50, decreased affinity):
  • Temperature ↑
  • PC02 ↑
  • 2,3-DPG ↑
  • pH ↓

MD / Nursing Order

• MD / Clinician initiates the transfusion order.
• Nurse (RN) creates the BB requisition for the transfusion.
• Compatibility Testing is usually ordered as a "Type & Cross," referring to blood typing and crossmatch.
• Type & Cross: In the nurse's mind, it means compatibility testing for ALL blood/blood components, even though it applies only to red cell-containing products (WB and RBCs).
• FFP or platelets are not crossmatched and do not contain RBCs, even if a nurse orders a Type & Cross for them.

3 Processing Phases of Compatibility Testing

1. Pre-Serologic Procedures
2. Serologic Testing Procedures
3. Post-Serologic Procedures

1. Pre-Serologic Procedures

• Specimen collection & Patient ID (Phlebotomy Dept)
• Specimen ID verification (Phleb & Lab)
• Specimen Meets Requirements / Specimen Age
• Review of patient's records (BB)

2. Serologic Testing Procedures

• ABO / Rh typing & ABS of patient specimen
• Ab ID performed, when ABS is positive
• ABO confirmation testing of RBC unit & Rh0(D) confirmation on all Rh neg labeled units
• Crossmatching of blood (random or screened) for transfusion

3. Post-Serologic Procedures

• Proper release of test results (manual or electronic)
• Proper labeling of RBC / blood component
• Proper release / distribution of RBC / blood component
• Proper transportation / storage, when applicable
• Proper re-release / re-distribution of RBC / blood component

Detailed Chronology of the Pretransfusion Process (5 Steps)

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STEP 1: Collection of Specimens / Types

• Patient
  • Patient ID verification - critically important to draw the correct patient
  • Use both patient RBCs and Serum / Plasma for testing
  • Usually use a BB pink top tube (K2 EDTA - dried form)
  • Alternate Specimens
    • Red top tube (clot) for antibody tests
    • Hematology plastic Lavender top tube (ensure K2 EDTA is the anticoagulant inside the tube - not the liquid form of K3 EDTA in the glass tube)
  • Make 3-5% patient cell suspension for testing

Patient Sample Label Requirements

• Patient's Name
• Medical Record Number
• Date & Time of Collection
• Initials of the person drawing the specimen

Specimen Criteria

• Patient
  • Non-hemolyzed
  • Free from IV contaminants
  • ≤ 3 days old
  • Retain this sample for 7 days following the transfusion date
• Donor
  • Non-hemolyzed
  • Must take pigtail / segment hermetically sealed AND attached to unit
  • Always retain 2 pigtails / segments for 7 days following transfusion date

SEROLOGIC TESTING PROCEDURES

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Compatibility Testing

• Recipient - For EVERY patient that is tested Always:
  • Check the BB patient history file to check previous testing or not
    • If patient has a prior history of having a clinically significant antibody, e.g., anti-K, you must always give antigen (K) negative blood - even if the current ABS result is negative
  • Perform ABO & Rh typing (Du testing may be optional)
  • Perform Ab Screen (ABS)
  • Perform Crossmatch (Xmat)

ABO Confirmation on Donor Unit

• Donor RBC / WB Unit Confirmations:
  • Every RBC / WB incoming unit from the blood supplier must be ABO confirmed
  • Rh0(D) confirmation is only required on all Rh neg RBC / WB units

Donor RBC / WB Unit Confirmation Process

• Using the attached pigtail / segment of the RBC / WB unit, make a 3-5% saline cell suspension. Never use a loose pigtail.
• ABO confirmation - perform only the Forward ABO typing for re-typing of all donor units
• Rh0(D) confirmation - only required on all Rh neg labeled units; usually Du test is NOT required to be performed, only IS test phase.

STEP 2: Patient Compatibility Testing Procedure, AKA, Type and Cross

• ABO
  • ABO typing is critical & must be performed correctly / interpreted correctly 100% of the time
  • Use automation (Gel or Solid Phase) OR manual (test tube)
  • A mismatch of ABO can result in an acute & severe HTR that could possibly result in immediate death of the patient dependent on the patient's condition
• Rh
  • Rh typing is also critical & must be performed correctly / interpreted correctly 100% of the time
  • Must match Rh…especially in child-bearing age (12 - 55 yrs) females to prevent severe HDFN / fetal demise
  • Use automation (Gel or Solid Phase) OR manual (test tube)
  • Du testing may be optional on the transfusing recipient

Patient Compatibility Testing Procedure, AKA, Type and Cross

• Ab Screen (ABS)
  • ABS is critical & must be performed correctly / interpreted correctly 100% of the time
  • Must detect clinically significant antibodies to prevent HTR or Delayed HTR, i.e., transfused RBCs can be destroyed (intra- or extra-vascular)
  • Use automation (Gel or Solid Phase) OR manual (test tube)
• Crossmatch (Xmat)
  • Xmat is critical & must be performed correctly / interpreted correctly 100% of the time

Patient Compatibility Testing Procedure, AKA, Type and Cross

• There are 2 methods to perform a crossmatch (Xmat):
  • Physical / Manual
  • Electronic
• TJC & CAP PT: Compatibility test must be 100% correct / accurate at ALL TIMES!

Xmat - Physical / Manual

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Patient Compatibility Testing Procedure, AKA, Type and Cross

• Crossmatch (Xmat) - physical
  • Manual
    • This is the serologic test using test tubes (TT)
    • Testing Phases are - IS, 37, & AHG
    • Use the same potentiating media as used in the ABS (e.g., LISS, PEG)
  • Automation
    • Use of automated equipment (Gel or Solid Phase)
    • Automation may have different Test Phases dependent on the equipment, media, etc.

The Physical Xmat

• CrossMatching (Compatibility Testing)

  • The compatibility testing includes, ABO and Rh typing on the donor and recipient blood samples screening of donor's and patient's sera for unexpected alloantibody detection and finally a cross match.
  • The crossmatching is two types: Major cross match & Minor crossmatch.
    • Major Crossmatch: Donor's cells + Patient's serum.
    • Minor Crossmatch: Donor's serum + Patient's cells.

• CROSSMATCH PHASES

Major vs Minor Xmat Crossmatching

• Major crossmatch:
  • If Major crossmatch is incompatible, then donor cells (which are less in volume) will react with antibodies in patient's plasma (which is large in volume) & will get destructed completely to cause serious hemolytic reaction. So it is called Major.
• Minor crossmatch:
  • If Minor crossmatch is incompatible, then donor's plasma (which is less in volume) will get diluted in patient's plasma (which is large in volume) and there are less chances of reaction between antibodies in donor's plasma with antigens on patients cells & so least chance of hemolytic reaction. So it is called Minor

Major Xmat

• Cross matching
  • The two main functions of the cross-match test can be cited as,
    • I-It is a final check of ABO compatibility between donor and patient.
    • 2-Detects clinically significant unexpected antibodies.

Minor Xmat

• MINOR CROSS MATCH TEST:
  • mixing the donor's plasma with patient's RBCs.
  • It is completely eliminated in most blood banks recipient cells are combined with donor plasma

TT (TEST TUBE) XMAT TEST PHASE - IS Immediate Spin Technique (IST)

• ✓ Detects only IgM antibody, reactive at 22^\circ C.
• ✓ Clinically significant IgG antibody reactive at 37^\circ C not detected

IMMEDIATE SPIN X-MATCH

• Aka- "abbreviated X-match"
  • *Perform only immediate spin phase if ABO/Rh type previously performed on R & R Abscreen is negative
  • *About 99.9% effective in detecting D/R incompatibilities
• ✓ Electronic X-.match as effective as the IS X-match(requires duplicate ABO/Rh groupings and negative Ab screen

TT XMAT TEST PHASE - 37 & AHG Conventional AHG-crossmatch

• Detects clinically significant (IgG) antibody

• \text{Patient serum} + \text{Donor RBC} \rightarrow \text{Incubation at } 37^\circ \text{C for 1 hr} \rightarrow 3 \text{ washes} + \text{2 drops AHG}

• No agglutination = compatible

• Agglutination = incompatible

TT XMAT PHASES

XMAT Limitations

• Limitations of Serological Testing

Xmat - Electronic

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Compatibility Testing Procedure, AKA, Type and Cross

• Xmat - electronic
  • Not a "serologic" test
  • BB computer software matches the recipient data (ABO / Rh, ABS, medical history) to each random donor unit(s) data (ABO / Rh type)
  • Requirement:
    • ✓ Performed only when the recipient's current ABS is negative
    • ✓ There is no history of any Abs
    • ✓ Must have current 2 ABOs, 2 Rhs, & 2 Ab Screens performed on 2 different specimens collected at 2 different times

Compatibility Testing Procedure, AKA, Type and Cross

• To expedit the overall Xmat Turn-around Time (TAT)
  • Usually the ABS & Xmat are performed simultaneously, since a majority of the patients have negative ABS, the Xmat will also be "compatible" to the RBC units.
  • It's only if the patient has an unexpected Ab will the TAT is extended.
  • Then you have to do an AB Id panel and possibly ag screen RBC units…added more time.

Selection of RBCs for Transfusion

POST-SEROLOGIC PROCEDURES

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STEP 3: Test Results Released

• After the recipient has been tested, the computer generates a Transfusion Record Form (TRF) / Tag.
• If there is no computer, then the CLS must manually write a form TRF.
• The TRF contains at a minimum the:
  1. Patient's full name
  2. Medical Record Number (MRN)
  3. DOB
  4. Hosp location
  5. Patient's ABO & Rh
  6. Unit #
  7. Unit ABO & Rh
  8. Unit expiration date
  9. Unit product code
  10. Other relevant attributes related to the unit, e.g., ag neg, CMV neg, low-titer, etc.

Transfusion Record Form (TRF)

• One TRF per Xmat unit or blood component is printed and tagged on each unit, e.g., 6 units Xmat & 2 blood components = 8 individual TRFs

Labeling the Donor Xmat Unit(S)

• Ensure the unit is labeled for its relevant attribute related to the patient, when applicable
• Must match each TRF to its appropriate corresponding unit
• The TRF is attached to each corresponding appropriate unit via a rubber band or plastic tie tag

Release / Distribution of the Xmat Unit

• Each Xmat unit(s) is / are checked AGAIN (by the CLS) just prior to distribution
• GOOD THING - If any errors are detected prior to distribution, the CLS can make corrections…only…& only at this time prior to distribution
• BAD THING - If any error is detected outside the Blood Bank, (e.g., on the hospital floor by the RN), this error is reportable / reviewed by the hospital Transfusion Committee and, if a patient death results, the error is reportable to the FDA.

Release / Distribution of the Xmat Unit

• If units need to be available for a surgery patient, the surgery dept usually has a centrally-located, designated BB refrigerator to temporarily store units.
• However, if the unit(s) need to be placed in a transport container for a surgery patient, the CLS must:
  • Ensure the packing of the unit(s) are correct
  • Place a temperature-control media inside the transporter to meet proper transportation / storage requirements*, as mandated by the regulations
  • The lid affixed to the container and is closed
  • The transport container displays the patient's name and MRN
• Transportation / storage temperature limits will be discussed in detail in the upcoming Blood Components lecture.

Re-Release / Re-Distribution of the RBCs / Blood Components

• Upon return of the transport container, the temperature of each actual RBC unit(s) / blood components must be measured.
• If the temperature is maintained at acceptable limits*, then the RBC unit(s) / blood components may be re-released / re-distributed at a later time.
• If the temperature is out-of-range, the unit(s) can NOT be issued.
• Transportation / storage temperature limits will be discussed in detail in the upcoming Blood Components lecture.