Post on 17-Dec-2015
Although there are over 600 known red blood cell antigens organized into 22 blood group systems, routine blood typing is usually concerned with only two systems: the ABO and Rh blood group systems. Antibody screening helps to identify antibodies against several other groups of red blood cell antigens.
Some of the other groups are the Duffy, Kell, Kidd, MNS, and P systems
2011YT Cartwright
2010DI Diego
3009JK Kidd
6008FY Duffy
3007LE Lewis
21006KEL Kell
18005LU Lutheran
47004RH Rh
1003P1 P
37002MNS MNSs
4001ABO ABO
BLOOD GROUP SYSTEMS
ANTIGENS ISBT NUMBER ISBT SYMBOL CONVENTIONAL NAME
*
*
BLOOD GROUP SYSTEMS
ANTIGENS ISBT NUMBER ISBT SYMBOL CONVENTIONAL NAME
- -
- -
- -
2
5
10
7
1
1
9
3
3
5
3
1
026JMH JMH
025RAPH Raph
024OK Ok
023IN Indian
022KN Knops
021CROMER Cromer
020GE Gerbich
019XK Kx
018H Hh
017CH/RG Chido/Rogers
016LW Landsteiner-Wiener
015CO Colton
014DO Dombrock
013SC Scianna
012XG0 Xg
Why do we have Anti-A or Anti-B Antibodies???
Viruses transmitted from the respiratory tracts of humans to
other humans drag along various antigens including ABO blood
group antigens. Prime the newborn’s immune
system.Reduces transmissibility of viruses within a population.
Population Distribution ofMajor Blood Groups
O Rh pos38%O Rh neg 7%A Rh pos34%A Rh neg 6%B Rh pos 9%B Rh neg 2%AB Rh pos 3%AB Rh neg 1%
Red blood cell compatibility table
AB+
AB-
B+
B-
A+
A-
O+
O-
AB+AB-B+B-A+A-O+O-
DonorRecipient
Plasma compatibility table
O
B
A
AB
AB
BAO
DonorRecipient
Other Blood Groups
No naturally occurring antibodiesImmune response requires
previous exposureWeaker titers of univalent antibodies
Why do we care?
Compatibility testing is done to avoida hemolytic transfusion reaction
If the Host or Recipient recognizesthe donor RBC surface antigens as foreign,the host will mount an immune response
to the donor RBC’s
Major Blood Groups
Rhesus47 Antigens make up the
Rhesus Blood GroupThe most significant is the
D antigen
There is no naturally occurringAnti D Antibodies
Production of Anti D in theRH negative recipient
requires previous exposureto the D antigen
(in utero or by transfusion)
If red cells are administeredto an ABO- or D-incompatible recipient,
the recipient will mount anantibody response to the foreign
RBC surface antigens
IgM is polyvalentand fixes complement
Clumps and extruded RBC stromaresult in organ dysfunction
and possible death
Incidence 1:38,000 – 1:70,000Mortality 1:30
Donor RBC’s coated with host antibodies
Stiffer RBC membraneSusceptible to attack by
splenic macrophages
Bits of Donor RBC membranelost traversing splenic sinusoids
(extravascular hemolysis)
SpherocytesDecreased RBC survival
Delayed anemiaPriming for worse reaction
What is compatibility testing?Also called pretransfusion testingPurpose:
To select blood components that will not cause harm to the recipient and will have acceptable survival when transfused
If properly performed, compatibility tests will confirm ABO compatibility between the component and the recipient and will detect the most clinically significant unexpected antibodies
Patient IdentificationMust confirm
recipient’s ID from bracelet ON the patientFull patient name
and hospital numberName of physician
http://www.usatoday.com/tech/news/techinnovations/2006-07-17-chips-everywhere_x.htm
COMPATIBILITY TESTINGCOMPATIBILITY TESTINGProcessing the specimen:Processing the specimen:
ABO Group determined (forward and ABO Group determined (forward and reverse)reverse)
D typing determinedD typing determinedAntibody screen will be performedAntibody screen will be performedABO/Rh identical or compatible blood ABO/Rh identical or compatible blood
will be made availablewill be made available
Sample IdentificationThe sample should
also have the full patient name, hospital number, and physician
Date and time of collection, phlebotomist’s initials
All of this should be on the request form and the sample
ABO/Rh TypingIn the ABO typing, the forward and reverse
MUST matchIn the Rh typing, the control must be
negativeBoth of these will indicate what type of blood
should be given
Front or Front or forwardforward type using monoclonal type using monoclonal anti-A and anti-B (commercial)anti-A and anti-B (commercial)
The sample is diluted to Hct 0.08, the The sample is diluted to Hct 0.08, the commercial antibodies added & the commercial antibodies added & the test tube is centrifugedtest tube is centrifuged
The RBC’s are then examined for The RBC’s are then examined for clumping (gross observation, gel clumping (gross observation, gel suspension)suspension)
Front or Front or forwardforward type using monoclonal type using monoclonal anti-A and anti-B (commercial)anti-A and anti-B (commercial)
The sample is diluted to Hct 0.08, the The sample is diluted to Hct 0.08, the commercial antibodies added & the commercial antibodies added & the test tube is centrifugedtest tube is centrifuged
The RBC’s are then examined for The RBC’s are then examined for clumping (gross observation, gel clumping (gross observation, gel suspension)suspension)
ABO TYPINGABO TYPING
ABO TYPINGABO TYPING
Back or Back or reverse reverse type with A and B cellstype with A and B cellsCommercially available A and B cells are Commercially available A and B cells are
added to two tubes of plasmaadded to two tubes of plasma
ABAB BB AA OO
A B A BA BA B
How do we know whether or not the host (or How do we know whether or not the host (or recipient) has antibodies to minor blood group recipient) has antibodies to minor blood group antigens?antigens?
How do we know whether or not the host (or How do we know whether or not the host (or recipient) has antibodies to minor blood group recipient) has antibodies to minor blood group antigens?antigens?
Add commercial RBC’s with known Add commercial RBC’s with known important minor antigens on their important minor antigens on their surface to host (or recipient) plasma surface to host (or recipient) plasma and centrifuge. Then incubate at and centrifuge. Then incubate at body temperature for 15-30 minutesbody temperature for 15-30 minutes
Then add rabbit antiglobulinThen add rabbit antiglobulin
Add commercial RBC’s with known Add commercial RBC’s with known important minor antigens on their important minor antigens on their surface to host (or recipient) plasma surface to host (or recipient) plasma and centrifuge. Then incubate at and centrifuge. Then incubate at body temperature for 15-30 minutesbody temperature for 15-30 minutes
Then add rabbit antiglobulinThen add rabbit antiglobulin
Antibody screenAlso called the Also called the indirect Coombs testindirect Coombs test or the or the
indirect antiglobulin testindirect antiglobulin testThe antibody screen will detect the
presence of any unexpected antibodies in patient serum
If antibodies are detected, identification should be performed using panel cells (with an autocontrol)IS37° (LISS)AHG
ANTIBODY SCREENINGANTIBODY SCREENING
Detection of unexpected clinically Detection of unexpected clinically significant antibodies against the minor significant antibodies against the minor blood group system antigensblood group system antigens
Positive in between 0 - 8% of samples Positive in between 0 - 8% of samples depending on the populationdepending on the population
2011YT Cartwright
2010DI Diego
3009JK Kidd
6008FY Duffy
3007LE Lewis
21006KEL Kell
18005LU Lutheran
47004RH Rh
1003P1 P
37002MNS MNSs
*
Possibly significant minor blood groups
SCREENING TEST RESULTS
A negative antibody screen allows blood to be dispensed using an immediate spin X-match or an electronic X-match, either of which confirms ABO compatibility
A positive antibody screen requires a full antiglobulin phase X-match
CrossmatchingPurpose:
Prevent transfusion reactionsIncrease in vivo survival of red cellsDouble checks for ABO errorsAnother method of detecting antibodies
Crossmatches According to the AABB Standards:
The crossmatch “shall use methods that demonstrate ABO incompatibility and
clinically significant antibodies to red cell antigens and shall include an antiglobulin
phase”
The procedureDonor cells are
taken from segments that are attached to the unit itself
Segments are a sampling of the blood and eliminate having to open the actual unit
Crossmatch Procedure if antibodies are NOT detected:
Only immediate spin (IS) is performed using patient serum and donor blood suspension
This fulfills the AABB standard for ABO incompatibility
This is an INCOMPLETE CROSSMATCHIf antibodies ARE detected:
Antigen negative units found and X-matchedAll phases are tested: IS, 37°, AHGThis is a COMPLETE CROSSMATCH
WillVerify donor cell ABO compatibility
Detect most antibodies against donor cells
Will NotGuarantee normal survival of RBCs
Prevent patient from developing an antibody
Detect all antibodies
Prevent delayed transfusion reactions
Type and Screen
Determines the ABO-Rh of the patient and the presence of the most commonly found unexpected antibodies(elimination of the crossmatch ).
Type and Screen
If an emergency transfusion is required after type and screen alone, an immediate-phase crossmatch is performed.
Blood given in this manner is more than 99% effective in preventing incompatible transfusion reactions due to unexpected antibodies.
Is the Crossmatch Really Needed?If the correct ABO and Rh blood type is
given, the possibility of transfusing incompatible blood is less than 1 chance in 1000.
ABO-Rh typing alone results in a 99.8% chance of a compatible transfusion,
The addition of an antibody screen increases the safety to 99.94%, and
A crossmatch increases this to 99.95%.
Physician responsibility in ordering uncrossmatched blood
In an emergency (ER or OR), there may not be enough time to test the recipient’s sample
It is your judgment that the risk of the patient dying from from anemia is greater than the risk of transfusing the patient without pre-transfusion testing
What can be given in an emergency?
Type-Specific, Partially Crossmatched Blood An ABO-Rh typing and an immediate-phase
crossmatchAn abbreviated format Macroscopic agglutination. This takes 1 to 5 minutes
What can be given in an emergency?Type-Specific, Uncrossmatched Blood
The ABO-Rh type Most ABO type-specific transfusions are
successful. Caution should be used for patients who have
previously received transfusions or have had pregnancies.
What can be given in an emergency?Type O Rh-Negative (Universal Donor),
Uncrossmatched Blood Type O blood lacks the A and B antigens Type O Rh-negative, uncrossmatched packed
RBCs should be used in preference to type O Rh-negative whole blood.
More than two units of type O Rh-negative, uncrossmatched whole blood, the patient probably cannot be switched to his or her blood type .
Specific Recommended Protocol1. Infuse crystalloids or colloids.2. Draw a blood sample for typing and
crossmatching.3. If crossmatched blood is not ready to give,
use type-specific or type O Rh-negative cells or type O Rh-positive cells for males or postmenopausal females without a history of transfusions.
SummaryThe crossmatch “shall use methods that
demonstrate ABO incompatibility and clinically significant antibodies to red cell antigens
If an emergency transfusion is required after type and screen alone, an immediate-phase crossmatch is performed before transfusion (an abbreviated format )
If crossmatched blood is not ready to give, use type-specific or type O Rh-negative cells