An ABO discrepancy occurs when the front and back type do not agree. The possible paterns can be deduced from the expected results.
Problem Front Type
Problem Back Type
False negative A antigen
False negative anti-A
False negative B antigen
False negative anti-B
False negative A and B antigens
False negative anti-A and False negative anti-B
False positive A antigen
False positive A and False negative B ags
False negative anti-B and False positive anti-A
False positive B antigen
False positive anti-B
False positive B and False negative A ags
False negative anti-A and False positive anti-B
False positive A and False positive B antigens
False positive anti-A and False positive anti-B
False positive anti-A
• Combinations in bold are unlikely since they involve both a false positive and a false negative.
• Results for anti-A,B are not included.
• Hypogammaglobulinemia could explain absence of all antibodies but would probably not explain the presence of one antibody but not the other.
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Specialty: Clinical Laboratory