CLS 3311
Advanced Clinical
Immunohematology
Compatibility (Pretransfusion)
Testing
Pretransfusion Testing
• Purpose: To select blood components that
will not cause harm to the recipient and will
have acceptable survival when transfused.
• When performed properly, pretransfusion
tests will confirm ABO compatibility
between the component and the recipient
and will detect most clinically
significant unexpected antibodies.
Pretransfusion Testing
Donor Basic Testing (processing):
• ABO Grouping: Forward and Reverse
• Rh typing: Complete with Weak D
• IAT: Antibody screen
• Transmissible disease testing: HIV, HTLV, HCV,
HBV and RPR
Recipient Basic Testing:
• ABO Grouping: Forward and Reverse
• Rh typing: Only Immediate is REQUIRED. Exception
is for neonates and women of child bearing age.
• IAT & Panel: Antibody Screen and Identification
Pretransfusion Testing
The Actual Crossmatch (X-m)
• Test DONOR CELLS with RECIPIENT SERUM
• May include I.S., 37oC, & AHG Phase (extended X-M)
• OR may just be Immediate Spin phase only to
confirm ABO compatibility of Recipient and Donor
• OR may be Computer Crossmatch !!
PURPOSE
• Detect Patient Antibodies that can react with
DONOR Cells
AABB Requirements for
Pretransfusion Testing
1. Positive identification of recipient and recipient sample
2. ABO group and Rh typing of recipient and donor blood.
3. Red cell antibody detection tests for clinically significant
antibodies using recipients serum or plasma.
4. Comparison of current findings of recipients sample with
record of previous patient results.
5. Selection of components of ABO group and Rh type
appropriate for the recipient.
6. Performance of a serologic or computer crossmatch.
7. Labeling of products with the recipients identifying
information.
Steps In Pre-transfusion Testing
Review available RECIPIENT Records
• Previous ABO & Rh and any PRIOR indication of
Unexpected antibodies
• For any Prior Adverse Reactions to transfusion
Donor Unit Id and ABO/Rh
• Confirm donor unit # with the collecting facilities
records, and confirm by retesting donor ABO/Rh
• Confirm match between donor unit ABO/Rh and the
patient ABO/Rh
Steps In Pre-transfusion Testing
Correct Identification of:
1. Recipient by confirming patient identity from
identification bracelet ON PATIENT
2. Recipient Sample by clear identification/
labeling on the recipient sample
– FULL patient name & unique hospital #,
– Name of requesting physician,
– Date and time of collection, & phlebotomist’s
initials
– Information clearly written on both the request form
and the sample itself
Steps In Pre-transfusion Testing
Collecting Patient Sample
• Sample must NOT be hemolyzed -
– Unless the patient is doing the hemolyzing
– Why?
• Can use serum or plasma
– Plasma prevents detection of complement dependent
antibodies and…
– Fibrin clots, which may form, can be mistaken for
agglutination
• If sample must be drawn from IV line:
– Infusion should be stopped for 5-10 minutes and the first 10
ml’s of sample discarded. Why?
Steps In Pre-transfusion Testing
Selection of Appropriate Donor Unit(s)
• ABO & Rh compatible
• Donor unit expiration date.
• Correct component preparation for the patient needs
such as thawing plasma, etc.
Accurate Testing & Recording Of
• Donor results: Computer data entry
• Recipient results: Computer data entry
• Do we ever make data entry errors in the laboratory?
Steps In Pre-transfusion Testing
AT THE TIME OF TRANSFUSION
Accurate Identification Of:
• Recipient pre-transfusion records
– Retrieve the correct patient’s records
• Correct donor unit is retrieved & released
• The correct recipient is identified on
unit/ward prior to initiating the component’s
infusion
Steps In Pre-transfusion Testing
• Recipient sample & Donor segment should be
stored at 1 to 6oC for minimum of seven days
• Transfusion should occur within 72 hours of
sample collection & testing
– Patients transfused or pregnant within the last 3
months, may be developing a clinically significant
antibody at a detectable level
– If sample used is > 72 hrs. post collection, a
clinically significant antibody may have formed and
will be missed. Only a new serum sample will pick
up the antibody.
Pre-transfusion Testing Procedures
TYPE & SCREEN
• Consists of ABO, Rh, IAT
• Ordered most often for Pre-Surgical Patient with:
– No abnormalities in ABO Grouping, Rh Typing
– No unexpected Ab’s detected with IAT
– No patient records of unexpected Ab’s or problems with
prior transfusions
• Patient ABO, Rh, & IAT are performed but no units
are crossmatched or reserved for the patient.
Pre-transfusion Testing
Procedures
Supplying blood for the
‘type & screen’ surgical patient
• Conservative Approach involves pulling the
patient sample and the appropriate donor unit
segments and doing an Extended Crossmatch
with IS, 37 and AHG phases.
• Moderate approach involves pulling the patient
sample and the appropriate donor unit segments
and performing an Abbreviated crossmatch
such as an Immediate Spin Crossmatch only.
Pre-transfusion Testing
Procedures
Liberal Approach: Computer Crossmatch
• Every keystroke in the computer system must be
validated.
• Donor Identification, ABO/Rh, IAT results entered
• Recipient Identification, ABO/Rh, IAT results entered
– Two different individuals must do the ABO (Rh) on the
same recipient specimen
– OR the same individual performs the ABO on 2
different collections of the same recipient
Pre-transfusion Testing
Procedures
Computer Crossmatch continued
• The test results are entered into a computer
that then selects the most appropriate Donor
unit in terms of ABO, Rh, & expiration
date for that recipient.
• Computer system contains logic to detect
and alert user of any discrepancies
between the recipient and donor.
• ‘Tube’ crossmatch is NOT performed.
Pre-transfusion Testing
Procedures
Extended Crossmatch
• Is to be Performed on Recipients with:
1. Unexpected antibodies
2. Prior records of unexpected antibodies OR
3. Problems with transfusion, ABO and/or Rh
• The Antibody(s) should be identified
prior to transfusion, if possible
– Some may not be possible to identify, such as auto
antibodies.
Pre-transfusion Testing Procedures
Special Circumstances
Extreme Emergency
• No time for even ABO and Rh testing
• Initially, the unit of choice is Gr O Rh Negative
• The Attending Physician must understand that a
sample must be obtained from the patient as
quickly as possible. Physician must sign waiver
omitting pre transfusion testing. Specimen
of choice is pretransfusion, if possible.
• If recipient is Rh Pos then the he/she can be
quickly switched to Rh Pos blood
Extreme Emergency
• The physician must sign a Release Form before you
release uncrossmatched blood for transfusion.
• This release indicates that the clinical condition
warrants the risks of transfusion in the absence
of knowing about the ABO, Rh, & IAT
• In cases where units are released without knowing the
Recipient’s ABO & Rh, the established protocol for
compatibility testing must be performed on the
Recipient & Donor units after the fact.
– Even if the units have already been transfused OR even if the
Recipient Dies. All work must be completed.
– All patient records must be complete.
Pre-transfusion Testing Procedures
Special Circumstances
Extreme Emergency Continued
• IF recipient is Rh Neg but has NO evidence of
anti-D, is male or beyond child bearing age, then
it may be more efficient to give Rh Pos blood
• If a recipient is hemorrhaging heavily, you will
end up replacing his blood volume more than
once
• If it is determined that giving Rh Pos units to an
Rh Neg patient is appropriate, the attending
Physician must be informed and consent
must be obtained in advance.
Pre-transfusion Testing Procedures
Special Circumstances
• Transfusing NON - ABO Group Specific Blood
– when the Recipient must be transfused the attending
Physician must be informed and agree.
• If group specific blood becomes available
and the choice is to switch to ABO group
specific blood, you MUST:
– Test for the presence of anti-A and/or anti-B in the
patient’s serum before returning to ABO group
specific blood
– If the Recipient doesn’t reverse group appropriately,
they should be given Gr O packed cells
Pre-transfusion Testing Procedures
Special Circumstances
Intrauterine & Infant Transfusions
• Blood must be compatible with MATERNAL
antibodies that are capable of crossing the placenta.
Crossmatch with Mom’s serum, if possible.
• If the ABO & Rh of the fetus or infant is known, then
group & type specific blood can be given
– if no fetomaternal incompatibility has been detected
• If the ABO & Rh are unknown, O Neg can be given
Pre-transfusion Testing Procedures
Special Circumstances
Massive Transfusion
• Replacement approximating or exceeding the
patients blood volume within a 24-hour period.
• If the patient has no unexpected Ab’s,
pretransfusion testing can be ELIMINATED
• If the patient has an unexpected antibody, the
units must be antigen typed, with commercial
antisera, for the corresponding antigen and
antigen negative blood must be transfused.