ABO Discrepancies Disclosure Objectives Importance Recognition ...

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4/12/2011 Forward Grouping Problems Mixed field (mf) agglutination Weak or missing antigens Additional or unexpected antigens Polyagglutinable cells Forward Grouping Problems Mixed Field (mf) Reactions Small agglutinates with many un-agglutinated cells Result of: Mixed cell population from a massive transfusion of another blood group. (non-O individual receiving O red blood cells) Bone marrow transplants having both the original type and donor marrow cells. The inheritance of weak ABO subgroups such as A 3 , A x and B 3 and B can traditionally present a mixed field reaction. Chimerism due to the intrauterine exchange of red cells, fraternal twins, and mosaicism arising from dispermy presents mixed field even though it rarely occurs. Forward Grouping Problems Resolving Mixed Field (mf) Reactions Determine the CAUSE of the mixed field reaction Checking the patient’s transfusion history and clinical history e.g. HPC transplant If it is determined that it is a weak subgroup, perform specialized tests e.g. adsorption and elution, saliva, and transferase studies Molecular testing Forward Grouping Problems Weak or Missing Antigen Result of: Inheritance of a weak ABO subgroup Malignancies may result in the loss of ABH transferases Hodgkins disease Lymphomas Leukemias Massive transfusion with group O blood to a non-group O person e.g. a group A person receiving lots of group O blood. Bone marrow transplant and chemotherapy. Forward Grouping Problems Resolving Weak or Missing Antigens Check the patient’s transfusion and clinical history Read the forward group microscopically Use anti-A,B and monoclonal antisera that is known to react with A x and dA 3 weak ABO subgroups Perform adsorption and elution studies Forward Grouping Problems Additional Antigens Result of: Bacterial enzymes deacetylate the A antigen to a “B” antigen and the patient front types as an AB and reverses as an A. Acquired B antigens are observed in patients with recurring GI or colon infections with Gram negative bacteria 4
4/12/2011 Forward Grouping Problems Resolving Additional Antigens Check clinical history for evidence of colon infections with Gram negative sepsis Test an auto control The patient’s own anti-B will not react with their own AB cells Acidify the anti-B to a p.H. of 6 and retest Acquired B antigens will not react in acidified antiserum, whereas as normal B antigens will react. Forward Grouping Problems Spontaneous Agglutination Result of: Strong potent cold auto antibodies Would appear as AB in the front type and O in the reverse type Strong positive DAT with IgG, C3d and saline control Wharton’s jelly in cord blood Forward Grouping Problems Resolving Spontaneous Agglutination Incubate plasma and cells (separately) at 37°C for 5 to 15 minutes ▪ Wash cells 5 to 6 times with warm saline ▪ Retest warm washed cells with warm plasma ▪ Retest the DAT and saline control Treat cells with 0.01M DTT Wash cord blood a minimum of 6 times with saline Forward Grouping Problems Polyagglutination Result of: Inheriting acquired abnormalities of the red cell membranes with exposure to crypt antigens e.g. T activation. Bacterially contaminated sample Resolve by: Avoid testing with human antisera; use monoclonal antisera. Collection of a new sample Reverse Grouping Problems ▪Plasma or serum ABO discrepancies are more common than red cell discrepancies. Reverse Grouping Problems Weak/Missing Additional Antibodies Rouleaux 5
Page 1 and 2: 4/12/2011 ABO Discrepancies Develop
Page 3: 4/12/2011 Types of ERRORS Clerical
Page 7 and 8: 4/12/2011 Reverse Grouping Problems
Page 9 and 10: 4/12/2011 Case Study #3: Patient Hi
Page 11 and 12: 4/12/2011 61 Anti-A Anti-B Anti-A,B
Page 13: 4/12/2011 73 References • Harmeni

ABO Discrepancies Disclosure Objectives Importance Recognition ...

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