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Transfusion > Week 9 > Flashcards

Week 9 Flashcards

ABO Anomalies

1
Q

What is an ABO anomaly?

A

A reaction that does not fit into the expected pattern for an ABO grouping.

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2
Q

What indicates a discrepancy in ABO grouping?

A

Any reaction where there is a mismatch between forward and reverse grouping.

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3
Q

What types of reactions are associated with ABO anomalies?

A

Weaker, missing, and unexpected reactions.

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4
Q

What should be done if an ABO grouping discrepancy repeats?

A

Additional testing should be performed to resolve the grouping.

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5
Q

When is it appropriate to assign a blood group in the presence of an ABO anomaly?

A

Never assign a blood group until the investigation is complete.

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6
Q

What should be done if an ABO anomaly cannot be resolved and the patient requires a transfusion?

A

Group O red cells and Group AB plasma should be given to the patient.

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7
Q

When is it appropriate to give group-specific blood to a patient with an ABO anomaly?

A

Only after the ABO anomaly is resolved.

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8
Q

What can affect sample integrity in testing?

A

Hemolysis of the sample.

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9
Q

What are the zones to consider in red cell suspension?

A

Pro-zone, equivalence zone, and post-zone.

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10
Q

How can incorrect sample collection impact testing?

A

Using the incorrect tube can affect test results.

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11
Q

What is a potential issue with reagents that can affect test integrity?

A

Reagents can become contaminated.

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12
Q

What equipment error can affect centrifugation in testing?

A

The centrifuge not spinning at the correct speed.

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13
Q

How does incorrect centrifugation time impact test results?

A

It can lead to incomplete or inaccurate separations.

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14
Q

What can happen if a sample is shaken too hard during resuspending?

A

It can cause cell damage or inaccurate resuspension.

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15
Q

What could cause incomplete antigen production?

A

Age-related factors or underdeveloped antigens.

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16
Q

How can disease affect antigen expression?

A

It can lead to missing or weak antigens or the presence of acquired or ‘pseudo’ antigens.

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17
Q

What could cause mixed reactions in antigen testing?

A

Transfusion-related issues.

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18
Q

What causes subgroups of A in blood typing?

A

Slight differences in A genes that code for different amounts of enzyme.

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19
Q

How do subgroups of A affect antigen presence on RBCs?

A

They result in fewer antigens on the RBC membrane and subtle differences in the antigen.

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20
Q

How do A1 antigens differ structurally from A antigens?

A

A1 antigens are both branched and linear, while A antigens are linear.

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21
Q

What two antigens are present on the red cell membrane in individuals with the A1 phenotype?

A

A1 and A antigens.

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22
Q

How does enzyme concentration relate to the A1 phenotype?

A

There is a high concentration of enzyme, resulting in more antigens on red cells.

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23
Q

What type of A antigens are present on the red cell membrane in the A2 phenotype?

A

Only linear A antigens, and in smaller amounts.

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24
Q

What reaction characteristics may individuals with the A2 phenotype show with Anti-A antisera?

A

They may have weaker reactions in forward reactions.

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25
Q

What antibodies are present in the plasma of individuals with the A2 phenotype?

A

Anti-A1 and Anti-B.

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26
Q

What type of red blood cell or plasma concentrate (PC) are individuals with the A2 phenotype given?

A

Group O RBC PC or A1 negative PC.

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27
Q

What are lectins?

A

Seed extracts that agglutinate with human red blood cells.

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28
Q

What is the origin of lectins?

A

They are plant-derived.

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29
Q

What is Anti-A1 lectin derived from, and how does it react?

A

Derived from Dolichos biflorus, it reacts with A1 cells but not A2.

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30
Q

Is Anti-A1 lectin from Dolichos biflorus the same as human Anti-A1 made by A2 individuals?

A

No, it is not the same.

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31
Q

What is Anti-H lectin derived from?

A

Ulex europaeus.

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32
Q

What reaction is typically seen with Anti-A or Anti-A,B reagents in rare A subgroups?

A

Weak or no reaction.

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33
Q

How do rare A subgroups react with Anti-A1 lectin?

A

No agglutination.

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34
Q

What may be present or absent in the serum of individuals with rare A subgroups?

A

Anti-A1.

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35
Q

What reaction occurs with Anti-H in rare A subgroups?

A

Strong agglutination.

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36
Q

Are adsorption and elution studies routinely performed for rare A subgroups?

A

No, they are not performed routinely.

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37
Q

What type of testing is used to confirm the genotyping of rare A subgroups?

A

Molecular testing.

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38
Q

What is the level of enzymes and antigens on red cells in newborns?

A

There are lower levels of enzymes and fewer antigens on red cells.

39
Q

How might reactions with antisera appear in cases of weak ABO antigen production?

A

Reactions with antisera may be weaker.

40
Q

What happens to antigen strength in certain diseases?

A

Antigen strength is depressed.

41
Q

Which conditions are associated with depressed antigen strength?

A

Leukemia, Hodgkin’s Lymphoma, and hematopoietic stress.

42
Q

How are A and B antigens affected in individuals with bone marrow stress?

A

They have weaker A and B antigens.

43
Q

In which types of cancer might ABO antigens become undetectable?

A

Stomach or pancreatic cancer.

44
Q

What is the association between stomach or pancreatic cancer and ABO antigens?

A

These cancers are associated with the loss of ABO antigens.

45
Q

What are acquired or pseudo-antigens?

A

Antigens that are not naturally occurring but appear due to certain conditions or diseases.

46
Q

In which patients is the “acquired B” antigen often found?

A

Group A patients with lower intestinal tract disorders like cancer, infection, or obstruction.

47
Q

How are some A antigens altered in disease?

A

They become more like the B antigen and may react with Anti-B antisera.

48
Q

Is Anti-B still detectable in patients with acquired B antigen?

A

Yes, Anti-B is still detectable in the patient’s serum.

49
Q

What will the patient’s blood contain after receiving Group O blood if they are A, B, or AB?

A

A mix of O RBCs and A, B, or AB RBCs.

50
Q

What reaction can be observed in patients with a mix of O RBCs and their original blood type?

A

Mixed field reactions (strong positive reaction with patient cells and un-agglutinated O cells in the background).

51
Q

Which patients can exhibit mixed-field reactions besides those receiving emergency transfusions?

A

Patients with bone marrow transplants.

52
Q

What could cause an expected antibody to be weak or missing?

A

Age (e.g., babies under four months and the elderly), disease (e.g., hypogammaglobulinemia or agammaglobulinemia), and immunosuppressive drugs.

53
Q

Why might infants under four months have weak or missing antibodies?

A

Babies do not produce antibodies until around four months of age.

54
Q

How can age affect antibody production in the elderly?

A

The elderly immune system produces fewer antibodies.

55
Q

Name two immune disorders that could lead to weak or missing antibodies.

A

Hypogammaglobulinemia and agammaglobulinemia.

56
Q

What are possible causes of unexpected antibodies or extra antibody reactions?

A

Subgroup of A, alloantibodies, autoantibodies, and rouleaux.

57
Q

What kind of antibodies are cold agglutinins, and at what temperature do they react optimally?

A

Autoantibodies that react optimally at room temperature.

58
Q

What is rouleaux, and how might it appear in antibody testing?

A

Rouleaux is a phenomenon where red blood cells stack together, which can appear as an extra antibody reaction.

59
Q

Should reverse typing tests be performed on babies under 4 months of age?

A

No, do not perform reverse typing tests on babies under 4 months of age.

60
Q

How is ABO typing determined in neonates?

A

By using forward grouping after washing the cells.

61
Q

What substance can interfere with ABO typing in neonates?

A

Wharton’s jelly.

62
Q

What antibody can an individual with the A2 phenotype produce?

A

Anti-A1.

63
Q

What antibodies are found in the plasma of individuals with the A2 phenotype?

A

Anti-A1 and Anti-B.

64
Q

What type of red blood cell products are given to individuals with the A2 phenotype?

A

Group O RBC PC or A1 negative PC.

65
Q

What is one method to test for antibodies reacting with RA/RB cells?

A

Test the serum against a different lot of RA/RB cells.

66
Q

What cells are used to further test for antibodies reacting with RA/RB cells?

A

Screen cells.

67
Q

What is a cold auto antibody, and how can it be identified?

A

A cold auto antibody reacts at lower temperatures; it can be identified by setting up a cold panel.

68
Q

How can interference from cold auto antibodies be minimized in testing?

A

Use the prewarm technique if the cold auto antibody is clinically insignificant.

69
Q

How can rouleaux appear in tubes during testing?

A

It can look like agglutination.

70
Q

How can you differentiate between rouleaux and true agglutination?

A

Perform a saline replacement of serum: rouleaux will disperse, but agglutination will remain.

71
Q

In which condition is rouleaux commonly seen?

A

Increased protein levels, often seen in patients with multiple myeloma (MM).

72
Q

What is the first step when investigating anomalies in a sample?

A

Repeat the sample.

73
Q

What should you check after repeating the sample?

A

Check all reagents and samples.

74
Q

Why is it important to retrieve patient history and diagnosis when investigating anomalies?

A

It provides relevant context for the investigation.

75
Q

How can test conditions be adjusted to help resolve anomalies?

A

Adjust test conditions to strengthen reactions.

76
Q

What additional step can be taken if anomalies persist?

A

Run additional tests using other reagent cells or antisera.

77
Q

What final step might be necessary if issues with the sample remain unresolved?

A

Collection of a new sample.

78
Q

Are cold antibodies typically significant in transfusion settings?

A

Cold antibodies are generally insignificant.

79
Q

Which testing methods might miss cold antibodies?

A

MTS and Capture R methods.

80
Q

Why might a cold antibody be undetectable in a Group O individual?

A

The cold antibody would be “masked” by the ABO antibodies.

81
Q

What should be done if a cold allo-antibody is detected?

A

The antibody must be worked up and identified.

82
Q

Why are cold antibodies considered a nuisance in transfusions?

A

They may interfere without being clinically significant, but could indicate the early production of a significant antibody.

83
Q

What type of immune response starts with IgM antibodies?

A

The initial immune response.

84
Q

How does the Bombay phenotype forward type?

A

It types as Group O, with no reactions with Anti-A, Anti-B, and Anti-A,B, but plasma reacts with both A1 and B cells.

85
Q

Are the antibodies in the Bombay phenotype naturally occurring?

A

Yes, they occur naturally, just as in other ABO types.

86
Q

What type of antibody is Anti-H in the Bombay phenotype?

A

Anti-H is an IgM antibody.

87
Q

What is a unique characteristic of Anti-H in the Bombay phenotype?

A

It binds complement and has a wide thermal amplitude.

88
Q

How does Anti-H react in antibody screening methods?

A

It reacts with antibody screens and panel cells in both MTS and solid phase methods.

89
Q

What is required for blood transfusion in individuals with the Bombay phenotype?

A

They must be transfused with blood from a Bombay donor.

90
Q

How do screening cells and panel cells react with Bombay phenotype plasma?

A

They would react with the plasma at room temperature (RT), 37°C, and in the Indirect Antiglobulin Test (IAT).

91
Q

What is the expected result for the auto control in the Bombay phenotype?

A

The auto control would be negative.

92
Q

Which lectin is used to type cells for the Bombay phenotype?

A

Lectin Anti-H from Ulex europaeus.

93
Q

Why is it important to find individuals with the Bombay (hh) phenotype?

A

They can be requested to donate and freeze their blood regularly for use in emergencies.

94
Q

What is a recommended practice for healthy Bombay phenotype individuals regarding their blood?

A

They should consider directed donation and freezing their blood.

Transfusion (8 decks)

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