Cross Matching 5e3w6j

CROSSMATCHING Albano, Astorga, Dumangon, Fregil, Gutierrez, Loque 4AMT Pretransfusion Compatibility Testing 

a.k.a. Compatibility Testing

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Series of testing procedures and processes with the ultimate objective of ensuring the best possible result (safety) of a blood transfusion

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The primary objective of the crossmatch test is to detect the presence of antibodies in the recipient’s serum that could destroy transfused RBCs.

Phases of Crossmatching Immediate Saline Spin Phase 

Also known as Protein / Albumin / Room Temperature phase

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Accomplished by mixing the patient’s serum with donor’s RBCs (Major) and the donor’s serum with patient’s RBCs (Minor) then centrifuge it immediately

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Absence of agglutination or hemolysis indicates compatibility

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Detects:

Crossmatch testing / Crossmatching 

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Traditionally meant the testing of the patient’s serum with the donor RBCs including an antiglobulin phase or simply an immediate spin phase to confirm ABO compatibility

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Incompatibility in ABO system

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Incompatibility due to cold antibodies

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Prozoning anti-Rh antibodies are detected in a serum albumin mixture on immediate centrifugation

Two main functions of serologic crossmatching: 

It serves as a final check of ABO compatibility between donor and patient.

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

Thermo Phase 

Also known as Incubation phase

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In this phase, the tubes showing no agglutination in the immediate spin phase will be incubated for 30 minutes at 37˚C water bath (10 mins if LISS is used instead of 22% BSA) then centrifuge

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No agglutination or hemolysis indicates compatibility

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Detects

It is divided into 2 parts: 

MAJOR Crossmatch 

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Patient’s serum + Donor’s red cells (PS-DR)

MINOR Crossmatch 

Donor’s serum+ Patient’s red cells (DS-PR)

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Incompatibility due to presence of low titered anti-Rh

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Certain Rh antibodies (anti-C, E and some D)

CROSSMATCHING Albano, Astorga, Dumangon, Fregil, Gutierrez, Loque 4AMT Antihuman Globulin Phase 

Also known as Coomb’s phase

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For greater sensitivity, AHG containing both anti-IgG and anti-complement may be used

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Prior coating of the donor’s RBCs with protein, resulting in positive AHG test

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Abnormalities in the patient’s serum

blend of rabbit anti-IgG and murine monoclonal anti-complement In this phase, the cells of tubes showing no agglutination in the previous phase are washed with NSS thrice. Next, AHG is added and then centrifuged.

No agglutination or hemolysis indicates compatibility

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Albumin/Globulin (A/G) ratio imbalance

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Presence of high molecular weight dextrans or other plasma expanders

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Antibody against additives in the albumin reagents

Problems Encountered 

Anti-Human Globulin AntiIgG, -C3d; polyspecific acts as a link between the antibody and/or complement coating of neighbouring red blood cells and induces agglutination. Uncoated red blood cells will not agglutinate.

Rouleaux formation 

In some diseases – myclomatosis macroglobulinemia

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Certain synthetic plasma expanders like dextran

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Fibrinogen

 Pan agglutination – spontaneous clumping of cells against a given serum

Detects 

Anti-Fya, -Jka, -K

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Antibodies present in acquired hemolytic anemia

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Antibodies in Rh system which react only in the AHG test (called 3rd order or cryoagglutinoid antibodies)

Causes of Positive Results in Crossmatching 

Incorrect ABO grouping of the patient or donor

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An alloantibody in the patient’s serum reacting with the corresponding antigen on donor’s RBCs

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An autoantibody in the patient’s serum reacting with the corresponding antigen on donor’s RBCs

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Bacteriogenic pan agglutination (Huebener-Thomsen Friedenreich phenomenon). Reaction takes place at 20C not at 37C.

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Non-bacteriogenic pan agglutination caused by acquired hemolytic anemia or by rare specific antibodies. Reaction takes place at 37C. DAT is always (+).

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Polyagglutinability

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Cold agglutinins

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Wharton’s jelly

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Prozones

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Ag-ab deterioration

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Presence of other immediate spin-reactive antibodies

CROSSMATCHING Albano, Astorga, Dumangon, Fregil, Gutierrez, Loque 4AMT 

Hyperimmune ABO antibodies

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Procedure is not performed properly

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Test should be performed at 37C

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Infants’ specimens are tested

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LISS instead of saline

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Contaminants in the test system

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2% suspension of donor red cell

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Enhancing agents (albumin, enzymes)

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Polycation or polybrine

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CASE

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2

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Procedures to shorten cross-matching time

SOLUTION: EDTA has been reported to eliminate some of the false-positive reactions

PROCEDURAL PHASE Protein Phase Thermo Phase AHG Phase Protein Phase Thermo Phase AHG Phase Protein Phase Thermo Phase AHG Phase Protein Phase Thermo Phase AHG Phase

CROSSMATCH MAJOR MINOR 0 0 0 0 0 0 + 0 0 0 + +

INTREPRETATION Blood is compatible in both major and minor crossmatch. Blood is safe for transfusion. Blood is incompatible in major crossmatch but compatible in minor crossmatch. Blood is not safe for transfusion Blood is incompatible both in major and minor crossmatch. Blood is not safe for transfusion.

0 0

+

Blood is compatible in major crossmatch but incompatible in minor crossmatch. Blood can be 0 transfused but with caution. Table 1.1 Summary of Interpretation of Crossmatching Results