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ABO DISCREPANCIES A Jean Purcelli, MT(ASCP)SBB Blood Centers of the Pacific.

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Presentation on theme: "ABO DISCREPANCIES A Jean Purcelli, MT(ASCP)SBB Blood Centers of the Pacific."— Presentation transcript:

1 ABO DISCREPANCIES A Jean Purcelli, MT(ASCP)SBB Blood Centers of the Pacific

2 ABO discrepancies occur because of: Intrinsic problems with the red cells or the serum. Test related problems—slide vs. tube Technical errors.

3 Intrinsic red cell problems Weaker subgroups of A and B or AB such as A 2, A x, A 3, A 2 B and subgroups of B. Variant A or B genes such as B(A). Must be differentiated from a subgroup of AB. A patient who has had a bone marrow transplant or an A or B recipient recently transfused with group O red cells. Intrinsic red cell problems Weaker subgroups of A and B or AB such as A 2, A x, A 3, A 2 B and subgroups of B. Variant A or B genes such as B(A). Must be differentiated from a subgroup of AB. A patient who has had a bone marrow transplant or an A or B recipient recently transfused with group O red cells.

4 Intrinsic red cell problems Acquired B. Usually associated with infections from GI (gastro-intestinal) bacteria Polyagglutinable state. The red cells are unexpectedly agglutinated by human source anti- A and Anti-B. Not seen with monoclonal antisera. Potent cold agglutinins Intrinsic red cell problems Acquired B. Usually associated with infections from GI (gastro-intestinal) bacteria Polyagglutinable state. The red cells are unexpectedly agglutinated by human source anti-A and Anti-B. Not seen with monoclonal antisera. Potent cold agglutinins Intrinsic red cell problems Acquired B. Usually associated with infections from GI (gastro-intestinal) bacteria Polyagglutinable state. The red cells are unexpectedly agglutinated by human source anti- A and Anti-B. Not seen with monoclonal antisera. Potent cold agglutinins Intrinsic red cell problems

5 Intrinsic problems in the serum Anti- A or –B is not usually detectable until 4-6 months of age. Any reactivity is usually maternal IgG forms of anti-A or –B. A2 or weaker subgroups of A or AB may produce anti-A1. Anti-A1 will react with A1 cells but not A2 or O cells. Allo-antibodies such as anti-M,-N,-P1, Lea or Leb May react at IS (immidiate spin)or RT(room temperature) and react with the A or B cells. Intrinsic problems in the serum

6 Intrinsic problems with the serum Abnormal concentrations of proteins or infusion with high molecular weight plasma expanders may show aggregation that is difficult to distinguish from true agglutination. Immunodeficient patient, due to disease or therapy may have decreased levels of anti-A or –B. Intrinsic problems with the serum Abnormal concentrations of proteins or infusion with high molecular weight plasma expanders may show aggregation that is difficult to distinguish from true agglutination. Immunodeficient patient, due to disease or therapy may have decreased levels of anti-A or –B. Intrinsic problems with the serum

7 Infusion of large volumes of compatible but not type specific plasma. Bone marrow transplants with compatible but dissimilar ABO groups. Example: a group A individual who receives group O marrow will produce circulating O cells, but produce only anti- B in the serum. Potent cold aggutinins. Intrinsic problems with the serum Infusion of large volumes of compatible but not type specific plasma. Bone marrow transplants with compatible but dissimilar ABO groups. Example: a group A individual who receives group O marrow will produce circulating O cells, but produce only anti- B in the serum. Potent cold aggutinins. Intrinsic problems with the serum

8 ABO discrepancies seen with test related problems Abnormal proteins, infusion of macromolecular solutions or improperly collected cord blood (contaminated with Wharton’s jelly) may cause false agglutination of cells. This is especially true when the cells are resuspended in serum which is usual for slide typing. ABO discrepancies seen with test related problems Abnormal proteins, infusion of macromolecular solutions or improperly collected cord blood (contaminated with Wharton’s jelly) may cause false agglutination of cells. This is especially true when the cells are resuspended in serum which is usual for slide typing. ABO discrepancies seen with test related problems

9 Problems with the test system Serum may contain antibodies to the dyes used to color anti-A and anti-B (USA) which may give false positives with serum- suspended cells in the slide test. Problems with the test system Serum may contain antibodies to the dyes used to color anti-A and anti-B (USA) which may give false positives with serum-suspended cells in the slide test. Problems with the test system

10 Resolving AB0 discrepancies Repeat the tests after washing patient cells and the A and B cells several times. Analyze the problem: 1. Unexptected + or unexpected – results? 2.What is unusual or different? 3.Do you see spontaneous agglutination? Resolving AB0 discrepancies Repeat the tests after washing patient cells and the A and B cells several times. Analyze the problem: 1. Unexptected + or unexpected – results? 2.What is unusual or different? 3.Do you see spontaneous agglutination? Resolving AB0 discrepancies

11 Resolving ABO discrepancies If the serum is unexpectedly positive, does the agglutination look like rouleaux? Use saline- replacement technique. Should you try to prove anti-A1 in an A2 person. Type patient cells with anti-A1 lectin. Test the serum with screening cells, and another set of A1 and A2 cells. Resolving ABO discrepancies If the serum is unexpectedly positive, does the agglutination look like rouleaux? Use saline- replacement technique. Should you try to prove anti-A1 in an A2 person. Type patient cells with anti-A1 lectin. Test the serum with screening cells, and another set of A1 and A2 cells. Resolving ABO discrepancies

12 Resolving ABO dicrepancies Is there strong hemolysis in reverse grouping tubes? Add another drop of appropriate cell and centrifuge again. Is the serum typing unexpectedly negative? Add several more drops of serum to all reverse grouping tubes, incuding the 3 O screening cells and an auto control. Incubate at RT or colder. Resolving ABO dicrepancies Is there strong hemolysis in reverse grouping tubes? Add another drop of appropriate cell and centrifuge again. Is the serum typing unexpectedly negative? Add several more drops of serum to all reverse grouping tubes, incuding the 3 O screening cells and an auto control. Incubate at RT or colder. Resolving ABO dicrepancies Is there strong hemolysis in reverse grouping tubes? Add another drop of appropriate cell and centrifuge again. Is the serum typing unexpectedly negative? Add several more drops of serum to all reverse grouping tubes, incuding the 3 O screening cells and an auto control. Incubate at RT or colder. Resolving ABO dicrepancies

13 Resolving ABO discrepancies If the discrepancy cannot be resolved, a patient should be transfused with group O red cells of the appropriate Rh type. A donor units may not be labelled or released for transfusion and should be discarded. Resolving ABO discrepancies If the discrepancy cannot be resolved, a patient should be transfused with group O red cells of the appropriate Rh type. A donor units may not be labelled or released for transfusion and should be discarded. Resolving ABO discrepancies If the discrepancy cannot be resolved, a patient should be transfused with group O red cells of the appropriate Rh type. A donor units may not be labelled or released for transfusion and should be discarded. Resolving ABO discrepancies

14 Refer to examples of paper ABO discrepancies And serological resolution Refer to examples of paper ABO discrepancies And serological resolution


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