COMPATIBILITY TESTING - kau.edu.sa

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COMPATIBILITY TESTINGCOMPATIBILITY TESTING

Dr. MOHAMMED H SAIEM Dr. MOHAMMED H SAIEM ALDAHRALDAHR

BLOOD BANKBLOOD BANK33RDRD MEDICAL TECHNOLOGY MEDICAL TECHNOLOGY

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Out line Out line Collection and Preparation of SamplesCollection and Preparation of SamplesCollecting Patient SamplesCollecting Patient SamplesDonor SamplesDonor SamplesSelection of Appropriate Donor UnitsSelection of Appropriate Donor UnitsTesting of the donor sampleTesting of the donor sampleTesting of the patient sampleTesting of the patient sampleCross-matchCross-matchSummary of Pre-transfusion TestingSummary of Pre-transfusion Testing

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As the knowledge of new blood group system As the knowledge of new blood group system increased, so did the search for more sensitive increased, so did the search for more sensitive pre-transfusion compatibility testing methods. pre-transfusion compatibility testing methods. Pioneer blood bankers mixed the patient’s serum Pioneer blood bankers mixed the patient’s serum and the donor’s red cells and observed for direct and the donor’s red cells and observed for direct red blood cells lysis, agglutination, or both. This red blood cells lysis, agglutination, or both. This became known as the major cross-match test.became known as the major cross-match test.

The term The term compatibilitycompatibility test and test and cross-matchcross-match are are some times used interchangeably, they should be some times used interchangeably, they should be clearly differentiated.clearly differentiated.

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The The cross-matchcross-match became became partpart of a series of of a series of pre-pre-transfusiontransfusion test known as test known as compatibility testingcompatibility testing. The . The compatibility test includes an compatibility test includes an ABO and Rh grouping ABO and Rh grouping performed on the donor and recipient samples, performed on the donor and recipient samples, screening of the donor’s and patient’s sera for screening of the donor’s and patient’s sera for unexpected antibodies, and a cross-match.unexpected antibodies, and a cross-match.

The The purposepurpose of pre-transfusion of pre-transfusion or compatibility or compatibility testing is to testing is to ensure the best possible results of a ensure the best possible results of a blood transfusion.blood transfusion.

The transfused red cells will have an acceptable The transfused red cells will have an acceptable survival rate, and there will be no significant survival rate, and there will be no significant destruction of the recipient’s own red cells.destruction of the recipient’s own red cells.

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Collection and Preparation of SamplesCollection and Preparation of Samples.. Positive Patient IdentificationPositive Patient IdentificationThe major cause of transfusion associated fatalities The major cause of transfusion associated fatalities have been have been clerical errors resulting in incorrect clerical errors resulting in incorrect ABO ABO groupinggrouping

The The most common causemost common cause of of clerical errorsclerical errors and thus and thus transfusion accidents is transfusion accidents is misidentification of the misidentification of the patient involved in the transfusion.patient involved in the transfusion. Confusion in Confusion in identification of the patient when the blood sample identification of the patient when the blood sample was drawn a mixed up samples during handling in was drawn a mixed up samples during handling in the lab, and error in identification of the patient the lab, and error in identification of the patient when the transfusion was given.when the transfusion was given.

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To prevent collection of samples from the wrong To prevent collection of samples from the wrong patientpatient, the blood , the blood request form must be used to request form must be used to confirm the patient’s identity before phlebotomy confirm the patient’s identity before phlebotomy is performedis performed.. The request form must state the The request form must state the intended recipient’s full name, and unique intended recipient’s full name, and unique hospital identification number.hospital identification number.

Other information such as Other information such as age and date of birth, age and date of birth, address, sex, and name of requesting physician address, sex, and name of requesting physician can be used to verify patient identity further but can be used to verify patient identity further but is not required on the form.is not required on the form.

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The patient’s wrist band identification must The patient’s wrist band identification must always be compared with the requisition form. always be compared with the requisition form.

If the patient does not have a wristband or if the If the patient does not have a wristband or if the patient’s identity is unknown, some form of patient’s identity is unknown, some form of positive identification must be attached to the positive identification must be attached to the patient before collection of samples.patient before collection of samples.

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Collecting Patient SamplesCollecting Patient SamplesHemolyzed samples can not be used for testingHemolyzed samples can not be used for testingbecause hemolysis caused by because hemolysis caused by activation of activation of

complementcomplement

Serum or plasma may be used for pre-transfusion Serum or plasma may be used for pre-transfusion testing. testing.

Most blood bank technologist prefer serum because Most blood bank technologist prefer serum because plasma plasma

may cause small fibrin clots to form which may may cause small fibrin clots to form which may difficult to difficult to

distinguish from true agglutination. distinguish from true agglutination.

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When a specimen is received in the lab, a blood When a specimen is received in the lab, a blood bank technologist must confirm that the bank technologist must confirm that the information on the sample and requisition form information on the sample and requisition form agree. agree.

All discrepancies must be resolved before the All discrepancies must be resolved before the sample is accepted, and if any doubt exists, a sample is accepted, and if any doubt exists, a new sample must be drawn. new sample must be drawn.

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Donor Samples.Donor Samples.Donor testing samplesDonor testing samples must be taken when the must be taken when the full donor unit is drawn. Depending on the full donor unit is drawn. Depending on the method used for testing, clotted sample, anti-method used for testing, clotted sample, anti-coagulated samples, or both, are obtained. coagulated samples, or both, are obtained. Donor informationDonor information and medical history card, the and medical history card, the pilot samples for processing, and the collection pilot samples for processing, and the collection bag must all be labeled with the same bag must all be labeled with the same unique unique number codenumber code before starting the phlebotomy, before starting the phlebotomy, and the numbers must be verified and the numbers must be verified again again immediately after fillingimmediately after filling..

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Donor and recipient samples must be stored for a Donor and recipient samples must be stored for a minimum of 7 days following transfusion.minimum of 7 days following transfusion.

The samples should be stoppered and The samples should be stoppered and refrigerated at 1-6°C, carefully labeled, and refrigerated at 1-6°C, carefully labeled, and adequate in volume so that they can be adequate in volume so that they can be re-re-evaluated evaluated if the patient experiences an adverse if the patient experiences an adverse response to the transfusion.response to the transfusion.

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Compatibility Testing ProtocolsCompatibility Testing Protocols..

Selection of Appropriate Donor Units.Selection of Appropriate Donor Units.

In almost all cases, In almost all cases, blood and blood components blood and blood components of the patient’s own ABO and Rh group should be of the patient’s own ABO and Rh group should be selected for transfusion. selected for transfusion.

When blood and blood components of the When blood and blood components of the patient’s type are patient’s type are unavailable or when some unavailable or when some other reason precludes their use, units selected other reason precludes their use, units selected must lack any Ag against which the patient has a must lack any Ag against which the patient has a significant Ab.significant Ab.

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Selection of Appropriate Donor Units.Selection of Appropriate Donor Units.

When transfusion of an ABO group different from When transfusion of an ABO group different from the recipient must be given, the recipient must be given, packed red cells packed red cells must be used rather than whole blood which must be used rather than whole blood which contains plasma Abs that are incompatible with contains plasma Abs that are incompatible with the patient’s red blood cells. the patient’s red blood cells.

Group Group O packed red blood cells can be safely O packed red blood cells can be safely used for all patients, however, conservation of a used for all patients, however, conservation of a limited supply of group O blood should dictate its limited supply of group O blood should dictate its use for patients of other AB types only in special use for patients of other AB types only in special circumstances.circumstances.

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Selection of Appropriate Donor UnitsSelection of Appropriate Donor Units..

If ABO-specific blood is not available or is in less than If ABO-specific blood is not available or is in less than adequate supply, alternative blood groups are chosen as adequate supply, alternative blood groups are chosen as summarized in the following table;summarized in the following table;

Patient ‘s BGPatient ‘s BG Alternative BG given as packed cellsAlternative BG given as packed cellsO NONEO NONEA OA OB OB O

AB A, B, OAB A, B, O only one of the three should be used for a given patientonly one of the three should be used for a given patient

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Rh-negative blood can be given to Rh-positive Rh-negative blood can be given to Rh-positive patients, however, good inventory management patients, however, good inventory management again should conserve this limited resource for again should conserve this limited resource for use in Rh-neg recipients.use in Rh-neg recipients.

If Rh-neg units is near expiration, the unit should If Rh-neg units is near expiration, the unit should be given rather than wasted. be given rather than wasted.

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Rh-pos blood should not be given to Rh-neg Rh-pos blood should not be given to Rh-neg women of childbearing age.women of childbearing age.

Transfusion of Transfusion of Rh-neg male patients and female Rh-neg male patients and female patients beyond menopause with Rh-pos blood is patients beyond menopause with Rh-pos blood is acceptable as long as no performed anti-D is acceptable as long as no performed anti-D is demonstrable in the serademonstrable in the sera. .

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Compatibility Testing Protocols.Compatibility Testing Protocols.

Testing of the donor sample.Testing of the donor sample.According to the According to the Code of Federal Regulation Code of Federal Regulation (CFR)(CFR) and the and the American Association of BB (AABB) American Association of BB (AABB) standardsstandards, , ABOABO and and Rh groupingRh grouping ( (including a test including a test for weak D)for weak D) and tests intended to prevent and tests intended to prevent disease disease transmissiontransmission must be performed on a sample of must be performed on a sample of blood taken at the time of collection of the unit of blood taken at the time of collection of the unit of blood from the donor.blood from the donor.

A screening test for A screening test for unexpected antibodiesunexpected antibodies to red to red blood cell Ags is required byblood cell Ags is required by AABB AABB standards on standards on samples from donors revealing samples from donors revealing a history of prior a history of prior transfusion or pregnancy. transfusion or pregnancy.

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Testing of the donor sampleTesting of the donor sample

The transfusing facility is required by AABB The transfusing facility is required by AABB standards to confirm the standards to confirm the ABO cell grouping on all ABO cell grouping on all units and Rh grouping on units labeled Rh-neg.units and Rh grouping on units labeled Rh-neg.

Tests for Tests for weak D (Dweak D (Duu) are not required to be ) are not required to be reported.reported. The transfusion facility does not need The transfusion facility does not need to repeat any other testing procedure. to repeat any other testing procedure.

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Testing of the patient sample.Testing of the patient sample.

A record of all results obtained in testing patient samples A record of all results obtained in testing patient samples must be maintained. must be maintained. Identification number should be assigned each time a Identification number should be assigned each time a patient is admitted for treatment. patient is admitted for treatment. Any discrepancies between previous and current results Any discrepancies between previous and current results must be resolved before transfusion is initiated. must be resolved before transfusion is initiated. A new sample should be collected from the patient, if A new sample should be collected from the patient, if necessary to resolve the problem.necessary to resolve the problem.ABO and Rh grouping results should be included in the ABO and Rh grouping results should be included in the file. file. Also, notations concerning Also, notations concerning unusual serologic reactions and unusual serologic reactions and the identity of unexpected Abs in the patient’s serum the identity of unexpected Abs in the patient’s serum should be included.should be included.

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Testing of the patient sampleTesting of the patient sample..

ABO and Rh grouping and Ab screening of the ABO and Rh grouping and Ab screening of the patient’s serum can be performed in advance of patient’s serum can be performed in advance of or at the same time as the cross-match. or at the same time as the cross-match.

If the patient has had a transfusion or has been If the patient has had a transfusion or has been pregnant within the last 3 months or if the pregnant within the last 3 months or if the history is unavailable or uncertain, the sample history is unavailable or uncertain, the sample must be obtained from the patient within 3 days must be obtained from the patient within 3 days of scheduled transfusion.of scheduled transfusion.

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ABO Grouping.ABO Grouping.Determination of the patient’s Determination of the patient’s correct ABO group correct ABO group is the most critical pre-transfusion serologic test.is the most critical pre-transfusion serologic test.

If the cell and serum grouping results do not If the cell and serum grouping results do not agree, additional testing must be conducted to agree, additional testing must be conducted to resolve the discrepancy. resolve the discrepancy. If the patient’s ABO group cannot be satisfactory If the patient’s ABO group cannot be satisfactory determined and immediate transfusion is determined and immediate transfusion is essential, essential, group O packed red blood cells should group O packed red blood cells should be used.be used.

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Rh Grouping.Rh Grouping.Rh grouping is performed using anti-D blood Rh grouping is performed using anti-D blood grouping serum. Tube or slide tests should be grouping serum. Tube or slide tests should be performed according to the manufacture’s performed according to the manufacture’s directions for the reagent, which may or may not directions for the reagent, which may or may not include the use of a suitable diluents control.include the use of a suitable diluents control.

Control must be run in parallel with Rh grouping Control must be run in parallel with Rh grouping tests performed on patient’s samples, to avoid tests performed on patient’s samples, to avoid incorrect designation of Rh neg, patient as Rh incorrect designation of Rh neg, patient as Rh positive. positive.

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Direct antiglobulin test (DAT) should be Direct antiglobulin test (DAT) should be performed on the patient’s red blood cells to performed on the patient’s red blood cells to determine whether uptake of autoantibody, determine whether uptake of autoantibody, (alloantibodies, if the patient’s has been recently (alloantibodies, if the patient’s has been recently transfused) is responsible for the positive control transfused) is responsible for the positive control result.result.

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If the Rh group of the recipient can not be If the Rh group of the recipient can not be determined and transfusion is essential, determined and transfusion is essential, Rh negative Rh negative blood should be given.blood should be given.

The test for The test for DDuu is unnecessary is unnecessary when testing when testing transfusion transfusion recipientsrecipients. Individuals typing as Rh neg . Individuals typing as Rh neg in direct testing should receive Rh-neg blood and in direct testing should receive Rh-neg blood and those typing as Rh pos in direct testing should those typing as Rh pos in direct testing should receive Rh pos blood. receive Rh pos blood.

As DAs Duu are considered Rh pos and may receive Rh pos are considered Rh pos and may receive Rh pos blood during transfusion.blood during transfusion.

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Antibody Screening.Antibody Screening.The The patient’s serum or plasma must be tested for patient’s serum or plasma must be tested for unexpected Abs. unexpected Abs. The aim of the Ab screening test is to detect as The aim of the Ab screening test is to detect as many clinically significant Abs as possible. many clinically significant Abs as possible. Clinically significant Abs refers to Abs that are Clinically significant Abs refers to Abs that are reactive at 37°C or in the DAT or both and are reactive at 37°C or in the DAT or both and are known to have caused a transfusion reaction or known to have caused a transfusion reaction or unacceptably short survival of the transfused red unacceptably short survival of the transfused red blood cells.blood cells.

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Testing of the patient sample.Testing of the patient sample.

Abs Regarded as always being potentially Abs Regarded as always being potentially clinically significantclinically significantABOABO RhRh KellKell DuffyDuffy Kidd S s UKidd S s U

Abs that may sometime be clinically SignificantAbs that may sometime be clinically SignificantLeLeaa p Lup Luaa Lu Lubb Cartwright. Cartwright.

Abs that rarely, if ever, are clinically significantAbs that rarely, if ever, are clinically significantLeLebb Chido/Rodgers (Ch Chido/Rodgers (Chaa/Rh/Rhaa) York, Sd Xg& Bg) York, Sd Xg& Bg

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Correct ABO grouping results are much more Correct ABO grouping results are much more critical to transfusion safety than Ab screening. critical to transfusion safety than Ab screening.

Most Abs, other than anti-A and anti-B do not Most Abs, other than anti-A and anti-B do not cause severe hemolytic transfusion reactions. cause severe hemolytic transfusion reactions. Thus the vast majority of patients would not Thus the vast majority of patients would not suffer grave consequences if transfused with suffer grave consequences if transfused with blood from ABO group compatible donor without blood from ABO group compatible donor without the benefit of Ab screening tests.the benefit of Ab screening tests.

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Detection of unexpected Abs is important, Detection of unexpected Abs is important, however, for the selection of donor red blood however, for the selection of donor red blood cells that are likely to survive maximally in the cells that are likely to survive maximally in the patient circulation. patient circulation.

Weakly reactive Abs that are capable of reacting Weakly reactive Abs that are capable of reacting with their Ags at 37°C can cause decreased with their Ags at 37°C can cause decreased survival of transfused incompatible red cells.survival of transfused incompatible red cells.

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Because large numbers of Ab molecules are Because large numbers of Ab molecules are present in the patient’s circulation compared present in the patient’s circulation compared with the number of red cells in a unit of blood, with the number of red cells in a unit of blood, incompatible donor cells are highly vulnerable to incompatible donor cells are highly vulnerable to destruction by patient Abs.destruction by patient Abs.

Abs screening offers several advantages over Abs screening offers several advantages over direct cross-matched testing for detection of Abs;direct cross-matched testing for detection of Abs;1- 1- Testing is performed using selected group O Testing is performed using selected group O red cells that are known to carry optimal red cells that are known to carry optimal representation of important blood group Ags.representation of important blood group Ags.

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2- 2- Testing can be performed well in advance of Testing can be performed well in advance of the anticipated transfusion, allowing ample time the anticipated transfusion, allowing ample time for identification of unexpected Ab and location for identification of unexpected Ab and location of suitable donor units lacking the corresponding of suitable donor units lacking the corresponding Ag.Ag.

Methods used to detect Abs in patient’s sera Methods used to detect Abs in patient’s sera must demonstrate all significant coating, must demonstrate all significant coating, hemolyzing, and agglutinating Abs active at 3 hemolyzing, and agglutinating Abs active at 3 7°C.7°C.

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Cross-matchCross-match

The two main functions of the cross-match test The two main functions of the cross-match test can be cited as,can be cited as,

I- I- It is a final check of ABO compatibility between It is a final check of ABO compatibility between donor and patient.donor and patient.

2- It may detect the presence of an 2- It may detect the presence of an Ab in the Ab in the patient’s serum that will react with Ags on the patient’s serum that will react with Ags on the donor RBCs but that was not detected in the Ab donor RBCs but that was not detected in the Ab screening because the corresponding Ag was screening because the corresponding Ag was lacking from the screening cell.lacking from the screening cell.

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Major and Minor cross-match testsMajor and Minor cross-match testsMajor cross-match test, consisting of mixing the Major cross-match test, consisting of mixing the patient’s serum with donor RBCs.patient’s serum with donor RBCs.

Minor cross-match testMinor cross-match test, consisting of , consisting of mixing the mixing the donor’sdonor’s plasma with plasma with patient’spatient’s RBCs RBCs

The minor cross-match test has been completely The minor cross-match test has been completely eliminated in most blood banks, because donor eliminated in most blood banks, because donor samples are screened beforehand for the more samples are screened beforehand for the more common Abs.common Abs.

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Method for major cross-match tests.Method for major cross-match tests.

Cross-match methods can be categorized by the Cross-match methods can be categorized by the test phase in which the procedure ends.test phase in which the procedure ends.

Immediate spin (IS) cross-match (Immediate spin (IS) cross-match (AbbreviatedAbbreviatedCross-match)Cross-match)

When no clinically significant Abs are detected When no clinically significant Abs are detected nor are there previous record of such Abs, a nor are there previous record of such Abs, a serologic test to serologic test to detect ABO incompatibility is detect ABO incompatibility is sufficient.sufficient.

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In IS (the patient’s serum with donor cell are In IS (the patient’s serum with donor cell are centrifuge immediately) centrifuge immediately) absence of hemolysis or absence of hemolysis or agglutination indicates compatibility.agglutination indicates compatibility.

False reaction may be seen in the presence of False reaction may be seen in the presence of other IS reaction other IS reaction (auto -I).(auto -I). In patient with In patient with hyperimmune ABO Abs, when the procedure is hyperimmune ABO Abs, when the procedure is not performed correctly (delayed in not performed correctly (delayed in centrifugation or reading) when rouleauex is centrifugation or reading) when rouleauex is observed, or when infant’s specimens are tested.observed, or when infant’s specimens are tested.

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Antiglobulin Cross-matchAntiglobulin Cross-matchThe procedure begin in the same manner as the The procedure begin in the same manner as the IS cross-match, continues to 37°C incubation and IS cross-match, continues to 37°C incubation and finishes with AHG test.finishes with AHG test.

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SUMMARYSUMMARYPRE TRANSFUSION TESTINGPRE TRANSFUSION TESTING

Is to provide safe, compatible blood for Is to provide safe, compatible blood for transfusion to each individual patient. The steps transfusion to each individual patient. The steps necessary for safe transfusion are:necessary for safe transfusion are:1. Accurate ABO and Rh typing of the patient.1. Accurate ABO and Rh typing of the patient.2. Accurate ABO and Rh typing of the donor.2. Accurate ABO and Rh typing of the donor.3. Screening tests for antibodies in the donors 3. Screening tests for antibodies in the donors and patients serum.and patients serum.4. In the presence of patient antibodies, selection 4. In the presence of patient antibodies, selection of appropriate units for each patient.of appropriate units for each patient.5. Compatibility Testing - (Major)5. Compatibility Testing - (Major)6. Accurate completion of paperwork and labels6. Accurate completion of paperwork and labels

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PRE TRANSFUSION TESTINGPRE TRANSFUSION TESTING

Compatibility TestingCompatibility TestingEach compatibility test is a unique experiment in Each compatibility test is a unique experiment in which an unknown (patient) serum and (donor) which an unknown (patient) serum and (donor) red cells are tested for the detection of red cells are tested for the detection of unexpected antibodies which are directed unexpected antibodies which are directed against antigens found on the cells. Negative against antigens found on the cells. Negative results indicate compatibility. This is one of the results indicate compatibility. This is one of the most important tests performed by a transfusion most important tests performed by a transfusion service.service.

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The purposes of compatibility testing are:The purposes of compatibility testing are:1. To detect irregular antibodies in the recipient 1. To detect irregular antibodies in the recipient serum that are directed against the donor’s cells.serum that are directed against the donor’s cells.2. To detect errors in ABO grouping.2. To detect errors in ABO grouping.3. To detect errors in labeling, recording, or 3. To detect errors in labeling, recording, or identifying donor’s or recipient’s samples.identifying donor’s or recipient’s samples.

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Compatibility testing does not:Compatibility testing does not:1. Ensure normal survival of donor red cells.1. Ensure normal survival of donor red cells.Prove that donor and or recipient serum is free of Prove that donor and or recipient serum is free of antibodies. Prevent immunization of the recipient.antibodies. Prevent immunization of the recipient.Detect ALL ABO typing errors.Detect ALL ABO typing errors.Detect errors in Rh typing of either recipient or Detect errors in Rh typing of either recipient or donor unless the recipient’s serum contains an donor unless the recipient’s serum contains an Rh antibody.Rh antibody.Detect ALL error of identification.Detect ALL error of identification.Pre-transfusion testing of the recipient must Pre-transfusion testing of the recipient must include an ABO and Rh typing, antibody screen, include an ABO and Rh typing, antibody screen, and a cross-match with all donor units. and a cross-match with all donor units.

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Patient red cell with –D AgPatient red cell with –D Ag . .

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If Rh –ve doIf Rh –ve do

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