4-ABO DISCREPANCIES Flashcards
(138 cards)
1
Q
What blood group has no antigens on red blood cells and reacts with both A1 and B cells in reverse grouping
A
Blood group O
2
Q
What blood group has A antigen on red blood cells and anti-B antibodies in plasma
A
Blood group A
3
Q
What blood group has B antigen on red blood cells and anti-A antibodies in plasma
A
Blood group B
4
Q
What blood group has both A and B antigens on red blood cells and no antibodies in plasma
A
Blood group AB
5
Q
What is the term for mismatch between red cell grouping and serum grouping results
A
ABO discrepancy
6
Q
What are common causes of ABO discrepancy
A
Clerical errors + Technical errors + Clinical discrepancy
7
Q
What is the first step in resolving ABO discrepancies
A
Repeat testing
8
Q
What should be checked during ABO discrepancy resolution
A
Clerical errors + Technical errors + Weakest reaction + Screening cells + Patient age + Diagnosis + Transfusion history
9
Q
What is the effect of weak or missing antibodies in newborns on ABO grouping
A
Unreliable reverse typing results
10
Q
What is the effect of age on antibody levels in ABO grouping
A
Decreased antibody production in elderly causing weak serum reactions
11
Q
What diseases can affect ABO grouping results
A
Leukemia + Lymphoma
12
Q
What is the impact of multiple blood transfusions on ABO grouping
A
Development of ABO discrepancies + Difficult crossmatching
13
Q
What is the relationship between forward and reverse typing in ABO grouping
A
Serve as check and balance following Landsteiner’s law
14
Q
What is the expected forward and reverse typing pattern for blood group O
A
Negative anti-A + Negative anti-B + Positive agglutination with A and B cells
15
Q
What is the expected forward and reverse typing pattern for blood group A
A
Positive anti-A + Negative anti-B + Positive agglutination with B cells
16
Q
What is the expected forward and reverse typing pattern for blood group B
A
Negative anti-A + Positive anti-B + Positive agglutination with A cells
17
Q
What is the expected forward and reverse typing pattern for blood group AB
A
Positive anti-A + Positive anti-B + Negative agglutination with A and B cells
18
Q
What is the first step when ABO discrepancy is suspected
A
Check clerical and technical errors before clinical discrepancy
19
Q
What common clerical errors cause ABO discrepancies
A
Worksheet mix-ups + Specimen mislabeling + Patient identification errors
20
Q
Why is a new sample requested when specimen collection errors are suspected
A
Ensure proper patient identification + Eliminate doubt + Ensure patient safety
21
Q
What is the mantra in blood banking regarding doubtful results
A
When in doubt repeat
22
Q
What is the preferred suspending medium for red cell suspension
A
0.85 to 0.9% normal saline solution
23
Q
Why should red cells not be suspended in patient serum or plasma
A
Causes masking or alteration of true ABO group
24
Q
What should be done if ABO discrepancy persists after proper sample and suspension preparation
A
Check patient age + Clinical diagnosis + Transfusion history
25
What are the three categories of ABO discrepancies
Clerical error + Technical error + Clinical discrepancy
26
What are the four clinical discrepancy groups
Group I + Group II + Group III + Group IV
27
What are key clerical practices to avoid ABO discrepancies
Immediate recording of results + Correct worksheet usage + Avoid wrong section recording
28
What technical errors can cause ABO discrepancies
Inadequate washing + Prozone/postzone effects + Sample mix-up + Missed hemolysis + Failure to add reagents or samples + Uncalibrated centrifuge + Over/under centrifugation + Contaminated reagents + Improper shaking
29
What is the effect of overcentrifugation
False positive results due to tightly packed cells
30
What is the effect of undercentrifugation
False negative results due to dispersed cells
31
What is the recommended washing procedure for red cells
Wash 3 to 4 times with saline
32
What causes prozone effect
Excess antibody leading to unbound immunoglobulin
33
What causes postzone effect
Excess antigen causing surplus antigen binding sites
34
What is the optimal ratio for antigen-antibody reaction in ABO testing
2 volumes serum + 1 volume 2-5% red cell suspension
35
What is the recommended procedure if technical errors are suspected
Review and correct technical factors + Repeat testing with new sample
36
What is the significance of clinical discrepancy
Problem lies within patient’s clinical condition affecting ABO typing
37
What clinical factors influence ABO discrepancies
Patient age + Diagnosis + Transfusion history
38
What is the priority in ABO discrepancy resolution
Patient safety and reliable test results
39
What is the first step when ABO discrepancy is suspected
Check clerical and technical errors before clinical discrepancy
40
What are common clerical errors causing ABO discrepancies
Worksheet mix-ups + Specimen mislabeling + Patient identification errors
41
Why is a new sample requested when specimen collection errors are suspected
Ensure proper patient identification + Eliminate doubt + Ensure patient safety
42
What is the preferred suspending medium for red cell suspension
0.85 to 0.9% normal saline solution
43
Why should red cells not be suspended in patient serum or plasma
Causes masking or alteration of true ABO group
44
What should be done if ABO discrepancy persists after proper sample and suspension preparation
Check patient age + Clinical diagnosis + Transfusion history
45
What are the three categories of ABO discrepancies
Clerical error + Technical error + Clinical discrepancy
46
What are the four clinical discrepancy groups
Group I + Group II + Group III + Group IV
47
What are key clerical practices to avoid ABO discrepancies
Immediate recording of results + Correct worksheet usage + Avoid wrong section recording
48
What technical errors can cause ABO discrepancies
Inadequate washing + Prozone/postzone effects + Sample mix-up + Missed hemolysis + Failure to add reagents or samples + Uncalibrated centrifuge + Over/under centrifugation + Contaminated reagents + Improper shaking
49
What is the effect of overcentrifugation
False positive results due to tightly packed cells
50
What is the effect of undercentrifugation
False negative results due to dispersed cells
51
What is the recommended washing procedure for red cells
Wash 3 to 4 times with saline
52
What causes prozone effect
Excess antibody leading to unbound immunoglobulin
53
What causes postzone effect
Excess antigen causing surplus antigen binding sites
54
What is the optimal ratio for antigen-antibody reaction in ABO testing
2 volumes serum + 1 volume 2-5% red cell suspension
55
What is the recommended procedure if technical errors are suspected
Review and correct technical factors + Repeat testing with new sample
56
What is the significance of clinical discrepancy
Problem lies within patient’s clinical condition affecting ABO typing
57
What clinical factors influence ABO discrepancies
Patient age + Diagnosis + Transfusion history
58
What is the priority in ABO discrepancy resolution
Patient safety and reliable test results
59
What characterizes Group I ABO discrepancy
Weak or missing antibodies causing unexpected reverse grouping reactions
60
What is the number one cause of Group I discrepancy
Age
61
What are common causes of Group I discrepancy
Newborns + Elderly + Leukemia + Immunosuppressive drugs + Immunodeficiency + Bone marrow transplant + Plasma exchange + ABO subgroups
62
How is Group I discrepancy resolved in newborns
Forward grouping only until 6 months of age
63
How can serum grouping reactions be enhanced in Group I discrepancy
Incubation at room temperature for 15-30 minutes + Centrifugation + Incubation at 4°C for 15-30 minutes
64
What test must be performed concurrently with 4°C incubation in Group I discrepancy
Autocontrol + O cell control
65
What is the purpose of autocontrol testing
Rule out autoantibodies and cold agglutinins
66
What characterizes Group II ABO discrepancy
Weak or missing antigens causing unexpected forward grouping reactions
67
What are common causes of Group II discrepancy
ABO subgroups + Leukemia + Lymphoma + Excess soluble blood group substances
68
What phenomenon is associated with Group II discrepancy and colon cancer
Acquired B phenomenon
69
What is the cause of ABO discrepancy due to excess soluble blood group substances
Neutralization of anti-A or anti-B reagents causing false negative or weak forward typing
70
What is the typical reaction pattern in forward and reverse typing for blood group O
No agglutination with anti-A and anti-B + Agglutination with A and B cells
71
What is the typical reaction pattern in forward and reverse typing for blood group A
Agglutination with anti-A + Agglutination with B cells
72
What is the typical reaction pattern in forward and reverse typing for blood group B
Agglutination with anti-B + Agglutination with A cells
73
What is the typical reaction pattern in forward and reverse typing for blood group AB
Agglutination with anti-A and anti-B + No agglutination with A and B cells
74
What is the method to enhance weak antigen reactions in Group II ABO discrepancies
Incubate test mixture at room temperature for up to 30 minutes
75
What is the next step if room temperature incubation does not resolve Group II discrepancy
Incubate at 4°C for 30 minutes with group O and autocontrol testing
76
Why include group O and autocontrol testing during 4°C incubation
To rule out autoantibodies and alloantibodies
77
What causes the acquired B antigen in Group II discrepancy
Bacterial enzymes modify N-acetyl D-galactosamine to D-galactosamine
78
What enzyme removes the acetyl group from A antigen specificity
Deacetylase
79
What is the effect of acquired B antigen on anti-B antisera reaction
Weak reaction with mixed-field appearance
80
How to resolve acquired B phenomenon
Test serum against autologous RBCs (negative reaction) + Avoid monoclonal anti-B clone ES4 + Modify antiserum pH + Perform secretor studies + Treat RBCs with acetic anhydride
81
What pH range prevents agglutination of acquired B antigen
Greater than 8.5 or less than 6
82
What characterizes Group III ABO discrepancies
Protein or plasma abnormalities causing rouleaux formation or pseudoagglutination
83
What diseases cause elevated globulin leading to rouleaux
Multiple myeloma + Waldenstrom's macroglobulinemia + Plasma cell dyscrasias + Hodgkin's lymphoma
84
What plasma substances cause rouleaux formation
Elevated fibrinogen + Plasma expanders like dextran + Polyvinylpyrrolidone
85
What is Wharton's jelly and its effect on ABO typing
Viscous mucopolysaccharide in cord blood causing red cell aggregation
86
How to resolve rouleaux caused by Wharton's jelly
Wash cord cells 6-8 times with saline
87
What is the saline replacement technique for resolving rouleaux
Remove serum + Replace with equal volume saline + Recentrifuge + Resuspend and read microscopically
88
What centrifuge speed and time is used in saline replacement
3500 rpm for 10-15 seconds
89
What is the purpose of saline replacement in ABO discrepancy
Differentiate true agglutination from rouleaux formation
90
What is the saline replacement technique
Remove serum + replace with equal volume saline + recentrifuge + resuspend + read microscopically
91
What is poly-agglutination resulting from inherited or acquired red cell membrane abnormalities exposing cryptic autoantigens
Group IV discrepancy cause I
92
What are self-antigens hidden or not readily recognized by the immune system under normal conditions
Cryptic autoantigens
93
What causes transient poly-agglutination due to bacterial enzymatic activity during infection
Exposure of cryptic antigens
94
What causes persistent poly-agglutination due to somatic mutation leading to enzyme deficiency exposing cryptic antigens
Persistent poly-agglutination
95
What is the autocontrol and Bovine Albumin Pool (BAP) result in poly-agglutination states
Negative
96
What are RBCs heavily coated with cold autoantibodies that spontaneously agglutinate independent of reagent antibody specificity
Group IV discrepancy cause II
97
What are unexpected ABO iso-agglutinins
Group IV discrepancy cause III
98
What are unexpected non-ABO alloantibodies
Group IV discrepancy cause IV
99
What test is used to rule out autoantibodies or cold agglutinins by mixing patient’s serum and red cells
Autocontrol test
100
What are the three phases of autocontrol testing
Immediate phase + Thermo phase + AHG phase
101
What is the treatment for cold autoantibody positive RBCs
Incubate at 37℃ + Wash with warm saline 3 times + Treat with 0.01M dithiothreitol (DTT)
102
What is the procedure for serum with cold autoantibodies
Warm reagent RBCs and serum to 37℃ for 10-15 minutes + Mix and test
103
What technique removes cold autoantibodies from patient serum
Cold auto-adsorption technique
104
What is the prewarming technique in ABO discrepancy resolution
Warm saline + tubes + reagents + patient serum and RBCs to 37℃ before testing
105
How is unexpected ABO iso-agglutinins resolved
Repeat serum grouping with multiple A1 + A2 + O cells + Perform autocontrol + Test patient red cells with Dolichos biflorus
106
How is unexpected non-ABO alloantibodies resolved
Perform antibody screening + Identification + Use A1 and B cells negative for corresponding antigen
107
What is pan-agglutination
Patient serum reacts with all reagent red cells masking clinically significant alloantibodies
108
How is pan-agglutination evaluated
Assess intensity of reactivity + Check autocontrol positivity
109
What causes forward grouping result O and reverse grouping result AB discrepancy in neonates
Weak or missing antibodies due to age
110
How is weak or missing antibody discrepancy resolved in reverse grouping
Prolong incubation at room temperature for 30 minutes + Centrifuge + If no reaction incubate at 4℃ for 30 minutes + Perform autocontrol
111
What characterizes Group II discrepancy
Unexpected weak or missing antigens causing forward grouping issues
112
What are common causes of Group II discrepancy
ABO subgroups + Leukemia + Lymphoma + Hodgkin’s disease + Excess soluble blood group substances + Acquired B phenomenon
113
What are blood group specific soluble substances that neutralize anti-A or anti-B reagents causing false negative forward typing
Glycoproteins in saliva + Urine + Other body fluids
114
What is acquired B phenomenon
Bacterial enzymes modify N-acetyl D-galactosamine to D-galactosamine resembling B antigen causing cross-reaction with anti-B antisera
115
What enzyme removes acetyl group from A antigen specificity in acquired B phenomenon
Deacetylase
116
How is acquired B antigen resolved
Test serum against autologous RBCs (negative reaction) + Avoid monoclonal anti-B clone ES4 + Modify antiserum pH >8.5 or <6 + Perform secretor studies + Treat RBCs with acetic anhydride
117
What characterizes Group III discrepancy
Protein or plasma abnormalities causing rouleaux formation or pseudoagglutination
118
What diseases cause elevated globulin leading to rouleaux
Multiple myeloma + Waldenstrom's macroglobulinemia + Plasma cell dyscrasias + Hodgkin's lymphoma
119
What plasma substances cause rouleaux formation
Elevated fibrinogen + Plasma expanders like dextran + Polyvinylpyrrolidone
120
What is Wharton's jelly
Viscous mucopolysaccharide in cord blood causing red cell aggregation
121
How is rouleaux caused by Wharton's jelly resolved
Wash cord cells 6-8 times with saline
122
What is the saline replacement technique
Remove serum + Replace with equal volume saline + Recentrifuge + Resuspend + Read microscopically
123
What centrifuge speed and time is used in saline replacement
3500 rpm for 10-15 seconds
124
What characterizes Group IV discrepancy
Miscellaneous causes including poly-agglutination + Cold autoantibodies + Unexpected ABO iso-agglutinins + Unexpected non-ABO alloantibodies
125
What causes ABO discrepancy where forward grouping shows blood group AB and reverse grouping shows blood group O
Rouleaux formation
126
What are the steps to resolve ABO discrepancy due to rouleaux formation
Check patient profile for diseases causing increased plasma protein + Visualize reaction under microscope to distinguish true agglutination from rouleaux + Perform saline replacement technique + Run antibody screen to confirm unexpected antibodies
127
What is the appearance of rouleaux formation under the microscope
Stacked coins
128
What technique replaces serum with NSS to resolve rouleaux
Saline replacement technique
129
What confirms rouleaux formation after saline replacement
Dispersion of RBCs
130
What is checked to confirm unexpected antibodies causing reverse grouping reactions
Antibody screen
131
What causes ABO discrepancy where forward grouping shows strong reaction with anti-B and weak reaction with anti-A
Cold autoantibodies
132
What is the cause of weak unexpected reaction in forward grouping
Weak reaction
133
What causes plasma agglutination with A1 cells and weak reaction in B cells in reverse grouping
Cold autoantibodies reacting with I antigen on adult red cells
134
What technique is used to resolve ABO discrepancy due to cold autoantibodies
Prewarming technique
135
What is included in prewarming technique
Warm saline + antisera + known RBC reagents + patient sample at 37C for 15 minutes before ABO procedure
136
What test confirms that patient cells are coated with antibodies in vivo due to cold autoantibodies
Direct antiglobulin test (DAT) or autocontrol
137
What is performed to confirm presence of unexpected antibodies in reverse grouping with cold autoantibodies
Antibody screening
138
What confirms that saline replacement has addressed rouleaux formation
Rbc dispersion
