2-ABO BLOOD GROUPING Flashcards
(267 cards)
1
Q
What law states that if an antigen is present on a patient’s red blood cells the corresponding antibody will not be present in the patient’s plasma under normal conditions
A
Landsteiner’s Law
2
Q
What blood group antigens share the same structural oligosaccharide chain
A
A + B + H antigens
3
Q
What is the RBC precursor substance or oligosaccharide chain called
A
Paragloboside
4
Q
What four sugar molecules compose the oligosaccharide chain on RBCs
A
Glucose + 2 D-galactose + N-acetylglucosamine
5
Q
What lipid anchors the oligosaccharide chain into the RBC membrane
A
Ceramide
6
Q
What enzyme attaches fucose or L-fucose to the RBC precursor substance forming the H antigen
A
L-fucosyltransferase
7
Q
Which gene encodes for the enzyme that forms the H antigen
A
H gene
8
Q
What enzyme does the A gene encode to form A antigen
A
Alpha-3-N-acetylgalactosaminyltransferase
9
Q
What enzyme does the B gene encode to form B antigen
A
Alpha-3-D-galactosyltransferase
10
Q
What sugar is the immunodominant sugar for B antigen
A
D-galactose
11
Q
What sugar is the immunodominant sugar for A antigen
A
N-acetylgalactosamine
12
Q
At what fetal age do ABH antigens begin to develop
A
5th week of fetal life
13
Q
What percentage of adult antigenic sites are present on red cells of newborns
A
Less than 50 percent
14
Q
At what age is A or B antigen expression fully developed
A
2 to 4 years of age
15
Q
What happens to antigen expression after 2 to 4 years of age
A
Remains constant throughout life
16
Q
What blood group system did Karl Landsteiner discover in 1900
A
ABO blood group system
17
Q
What are the four ABO blood groups
A
A + B + AB + O
18
Q
What blood group has antigen A and β-antibody in serum
A
A group
19
Q
What blood group has antigen B and α-antibody in serum
A
B group
20
Q
What blood group has both A and B antigens and no antibodies in serum
A
AB group
21
Q
What blood group lacks A and B antigens but has both α and β antibodies in serum
A
O group
22
Q
What is the structural basis shared by A B and H antigens
A
Common oligosaccharide chain
23
Q
What is the role of the H antigen
A
Precursor for A and B antigen formation
24
Q
What is the consequence of incompatible blood transfusion according to Landsteiner’s findings
A
Agglutination and transfusion reaction
25
When do ABO antibodies typically appear in life
3 to 6 months of age
26
When do ABO antibodies reach adult levels
5 to 10 years of age
27
Are ABO antibodies present in newborns
No
28
Are ABO antibodies naturally occurring or require antigenic stimulus
Naturally occurring
29
What term better describes ABO antibodies produced in response to environmental antigens
Non-red blood cell stimulated antibodies
30
What antibody occurs as IgG or IgM alloantibodies in Bombay phenotype individuals
Anti-H
31
What makes anti-H clinically significant
Thermal range + Ability to activate complement
32
In which ABO types is H antigen present in lowest concentration
A1 + A1B
33
Why can anti-H be weak in A1 and A1B individuals
Low concentration of H antigen
34
Why is anti-H strong in Bombay phenotype individuals
Complete absence of H antigen
35
What antibody is directed against the A antigen
Anti-A
36
In which blood groups is anti-A found
B + O
37
What is the primary immunoglobulin class of anti-A antibody
IgM
38
Which immunoglobulin class of anti-A may be present in group O individuals
IgG
39
What can anti-A cause if A-positive blood is transfused into someone with anti-A
Agglutination + Hemolysis
40
What type of donor blood contains A antigen
A-positive packed red blood cells
41
What type of donor blood contains B antigen and anti-A antibody
B-positive whole blood
42
Why do group B individuals have anti-A antibodies
Because they lack A antigen on their red blood cells
43
What antibody reacts with both A and B antigens
Anti-A
44
In which individuals is anti-A
B commonly found
45
What can anti-A
B be composed of
46
Are anti-A
B reagents lab-made or naturally occurring
47
What is the use of anti-A
B reagents in blood typing
48
What immunoglobulin class are most anti-A
B antibodies
49
What immunoglobulin class of anti-A
B is seen in group O mothers exposed to fetal red cells
50
According to Landsteiner’s rule what antibody is present in plasma of group A individuals
Anti-B
51
According to Landsteiner’s rule what antibody is present in plasma of group B individuals
Anti-A
52
What antibodies are absent in plasma of group AB individuals
Anti-A + Anti-B
53
What antibodies are present in plasma of group O individuals
Anti-A + Anti-B + Anti-A
54
What is the universal donor blood group for packed red blood cells
Group O
55
Why is blood group O the universal donor for packed red blood cells
No A or B antigens on red cells
56
Why is blood group AB the universal donor for plasma
No antibodies in plasma
57
What antibody is present in blood group A recipient plasma
Anti-B
58
Why does blood group O packed RBC not cause hemolysis in blood group A recipient
No B antigen on O RBC
59
What antibody is present in blood group B recipient plasma
Anti-A
60
Why does blood group O packed RBC not cause hemolysis in blood group B recipient
No A antigen on O RBC
61
Why does blood group AB recipient not react to blood group O packed RBC
AB has no antibodies
62
Why is blood group AB packed RBC not a universal donor
Presence of A and B antigens
63
What antibodies are present in blood group O recipient plasma
Anti-A + Anti-B + Anti-AB
64
Why does blood group AB packed RBC cause transfusion reaction in blood group O recipient
Anti-A and Anti-B antibodies attack A and B antigens
65
Why does blood group AB packed RBC cause transfusion reaction in blood group B recipient
Anti-A antibody attacks A antigen
66
Why does blood group AB packed RBC cause transfusion reaction in blood group A recipient
Anti-B antibody attacks B antigen
67
What is the universal donor blood group for packed red blood cell transfusion
Blood group O
68
What is the universal donor blood group for plasma transfusion
Blood group AB
69
Why is blood group AB plasma safe for all recipients
No antibodies to attack recipient antigens
70
Why is blood group O plasma not a universal donor
Contains anti-A + anti-B + anti-AB antibodies
71
Can blood group A recipient safely receive blood group O plasma
No
72
Why is blood group O plasma unsafe for blood group A recipient
Anti-A antibodies attack A antigens
73
Can blood group B recipient safely receive blood group O plasma
No
74
Why is blood group O plasma unsafe for blood group B recipient
Anti-B antibodies attack B antigens
75
What tests must be included in routine ABO grouping
Forward typing + Reverse typing
76
Why should serum or antisera be added before cells in ABO testing
To avoid forgetting reagent addition
77
Why is immediate recording of ABO test results important
Prevent technical + clerical errors
78
What causes hemolysis during ABO blood grouping tests
Complement activation destroying red blood cells
79
What materials are needed for ABO blood grouping by test tube method
Test tubes + Dropper + Anti-A + Anti-B sera + Centrifuge + Blood sample + Reagent red cells
80
What materials are used for ABO blood grouping by slide method
Slides + Anti-A + Anti-B sera + Blood sample
81
What are anti-sera used for in forward typing
Detect specific antigens on red blood cells
82
What type of antibodies do monoclonal anti-sera contain
Antibodies from a single B cell clone
83
What type of antibodies do polyclonal anti-sera contain
Mixture of antibodies from multiple B cell clones
84
Why are anti-sera color-coded
Enhance contrast and minimize interpretation errors
85
What color is anti-A anti-sera
Blue
86
What color is anti-B anti-sera
Yellow
87
What dye is used in polyclonal anti-A anti-sera
Trypan blue
88
What dye is used in monoclonal anti-A anti-sera
Brilliant blue FCF
89
What dye is used in polyclonal anti-B anti-sera
Acriflavine
90
What dye is used in monoclonal anti-B anti-sera
Tartrazine
91
What is the recommended storage temperature for anti-sera
2 to 8 degrees Celsius
92
What is the main advantage of polyclonal anti-sera
High sensitivity due to multiple epitope recognition
93
What is the main advantage of monoclonal anti-sera
High specificity to a single epitope
94
How are monoclonal antibodies produced
Hybridoma technology involving fusion of B cells with myeloma cells
95
What is the first step in monoclonal antibody production
Immunization of mouse with specific antigen
96
What cells are harvested from the mouse for monoclonal antibody production
Antibody-producing B cells from spleen
97
Cell formed by fusion of B cells and myeloma cells producing specific antibodies and capable of indefinite division
hybridoma
98
Why are monoclonal antibodies preferred for precise testing
Consistent specificity and uniformity
99
What is the recommended condition for blood samples used in blood grouping
Fresh samples stored at 2 to 8 degrees Celsius tested within 3 days
100
Why are hemolyzed samples unsuitable for blood grouping
Hemolysis interferes with agglutination observation causing false negatives
101
What red cell suspension concentration is used for test tube ABO typing
2 to 5 percent
102
What red cell suspension concentration is used for gel technology ABO typing
0 to 8 percent
103
What ABO typing techniques are commonly used
Slide test + Tube technique + Microplate + Gel card system
104
Why is reagent added before red cell suspension in ABO testing
To avoid forgetting reagent addition
105
Why is immediate recording of ABO test results important
Prevent technical and clerical errors
106
What causes hemolysis during ABO blood grouping tests
Complement activation destroying red blood cells
107
What is the first step in the slide method for ABO blood typing
Take a dry and clean glass slide
108
What is drawn on the slide in the slide method
Ceramic rings labeled Anti-A and Anti-B
109
What is added to each ring in the slide method
One drop of Anti-A sera and one drop of Anti-B sera
110
What is added after anti-sera in the slide method
One drop of red cell suspension
111
How is the mixture handled in the slide method
Mixed well with separate application sticks
112
How is agglutination observed in the slide method
By tilting the slide back and forth
113
What are advantages of the slide method
Quick + Easy + Simple equipment
114
What are disadvantages of the slide method
Less sensitivity + Dries easily + False positives
115
Why is the slide method considered obsolete
Not reliable for blood typing results
116
How long should you observe the slide for agglutination
2 minutes
117
What indicates a positive result in the slide method
Agglutination occurs
118
What indicates a negative result in the slide method
No agglutination occurs
119
What test is more reliable than the slide method
Test tube method
120
What enhances the reaction in the test tube method
Longer incubation + Centrifugation
121
What can the test tube method detect better than the slide method
Weaker antigen-antibody reactions
122
What is the gold standard for ABO blood grouping
Test tube method
123
What are the two essential components of the ABO test
Forward grouping + Reverse grouping
124
What is done in forward grouping
Detect ABO antigens on red blood cells using anti-A and anti-B antisera
125
What is the concentration of cell suspension used in forward grouping
2 to 5 percent
126
What is the centrifugation speed and time in forward grouping
1000 to 1500 rpm for 1 minute
127
What is checked after centrifugation in forward grouping
Hemolysis + Agglutination
128
What is done in reverse grouping
Detect antibodies in serum using known A B and O cell suspensions
129
What is the centrifugation speed and time in reverse grouping
1500 rpm for 1 minute
130
What is the purpose of reverse grouping
Confirm forward grouping results
131
What ABO blood group shows no agglutination in forward grouping but positive in reverse grouping
Blood group O
132
What ABO blood group shows agglutination with anti-A and reacts with B cells in reverse grouping
Blood group A
133
What ABO blood group shows agglutination with anti-B and reacts with A1 cells in reverse grouping
Blood group B
134
What ABO blood group shows agglutination with both anti-A and anti-B and no reaction in reverse grouping
Blood group AB
135
What method is sensitive and ideal for testing large numbers of blood samples
Microplate method
136
What does a microplate consist of
96 U- or V-shaped micro wells
137
What method uses gel cards with microtubes containing dextran acrylamide gel and anti-serum
Gel technology
138
What indicates a negative reaction in gel card testing
Red blood cells sediment at bottom of microtube
139
What ABO blood typing techniques are performed manually
Slide test + Tube technique + Microplate
140
At what temperature is ABO typing classically performed
Room temperature
141
What is the grading scale for agglutination results
4+ solid agglutinate to 0 no agglutination
142
What background clarity is associated with strong agglutination (4+)
Clear
143
What background clarity is associated with weak agglutination (+/-)
Turbid
144
What numerical representation is used to describe the strength of antibody-antigen reaction in ABO grouping
Grading of results
145
Why is ABO grading considered semi-quantitative and not quantitative
Estimated strength of agglutination reaction without exact antibody-antigen complex count
146
Where is the ABO grading system used in PHC documented
SOP + Worksheets + Logbooks + Requisition forms
147
What does a 1+ grade indicate in ABO blood grouping
Very small agglutinates difficult to observe microscopically
148
In which ABO typing are 1+ and 2+ reactions usually observed
Serum typing
149
Why are weaker reactions typically seen in serum typing
Poor quality of known red cell reagent or donor blood pool
150
How can small clumpings in 1+ and 2+ grades be better appreciated
Microscopically
151
Is it acceptable to check 1+ and 2+ agglutination microscopically
Yes
152
Why check small aggregates microscopically in ABO grading
Differentiate true clumping from rouleaux formation
153
What symbol is used for trace reactions in ABO grading
+/-
154
How are mixed field reactions best appreciated in ABO grading
Microscopically
155
What is seen microscopically when no agglutination occurs
Red cells free flowing and apart in supernatant
156
What is the proper way to examine agglutination reactions in tube method
Hold tube upright and slightly tilted
157
Why should shaking be gentle during agglutination examination
Vigorous shaking destroys agglutination
158
What can vigorous shaking cause in ABO testing
Mixed field reactions
159
Why is serum typing more sensitive than forward typing
Weaker reactions and overmixing more common in serum testing
160
What formation can interfere with reading ABO results
Rouleaux formation
161
How does rouleaux formation appear microscopically
Stack of coins
162
Why must ABO grading results be documented
Avoid clerical errors + Provide records for 10 to 15 years
163
Why are blood typing and cross-matching records kept for 10 to 15 years
For investigation + Medicolegal evidence
164
What can result from not documenting ABO grading immediately
Clerical errors + ABO discrepancy
165
What is the common reason for documentation policies in hospitals
Avoid clerical errors + Maintain long-term records
166
What does ABO discrepancy mean
Mismatch between red cell grouping and serum grouping results
167
What are the causes of ABO discrepancies
Clerical errors + Technical errors + Clinical discrepancies
168
What is the expected forward and reverse grouping for blood group O
No agglutination with anti-A and anti-B + Agglutination with A cells and B cells
169
What is the expected forward and reverse grouping for blood group A
Agglutination with anti-A + Agglutination with B cells
170
What is the expected forward and reverse grouping for blood group B
Agglutination with anti-B + Agglutination with A cells
171
What is the expected forward and reverse grouping for blood group AB
Agglutination with anti-A and anti-B + No agglutination with A cells and B cells
172
What indicates an ABO discrepancy in blood typing results
Forward and reverse typing results do not match
173
What is the gold standard method for ABO blood grouping
Test tube method
174
What is the first step in investigating ABO discrepancy
Check for clerical or technical errors
175
What should be done if sample or identification error is suspected in ABO discrepancy
Re-extract blood sample and repeat test
176
What is the purpose of washing patient RBCs with saline in ABO discrepancy investigation
Remove antibodies in plasma or serum causing false reactions
177
What should be considered after ruling out sample issues in ABO discrepancy
Patient medical history and clinical diagnosis
178
What is the role of serum typing in ABO grouping
Confirm forward typing results and check for discrepancies
179
What is the significance of strong reactions (3+ to 4+) in ABO grouping
Usually indicate no discrepancy
180
What does a weak reaction in RBC or serum grouping usually represent
ABO discrepancy
181
What is the common cause of ABO discrepancy in forward typing
Weak or missing antigen reactions
182
What is the common cause of ABO discrepancy in reverse typing
Weak or missing antibody reactions
183
What is the recommended action if forward and reverse typing results differ
Repeat ABO/Rh tests and check specimen quality
184
What is the principle of reverse blood grouping
Detect antibodies in serum reacting with known A and B red cells
185
What is the importance of concordance between forward and reverse typing
Confirm accurate ABO blood group determination
186
What is the clinical significance of ABO discrepancies
Potential transfusion reactions if unresolved
187
What is the typical reaction pattern for blood group A in forward and reverse typing
Positive anti-A + Negative anti-B + Positive agglutination with B cells
188
What is the typical reaction pattern for blood group B in forward and reverse typing
Negative anti-A + Positive anti-B + Positive agglutination with A cells
189
What is the typical reaction pattern for blood group AB in forward and reverse typing
Positive anti-A + Positive anti-B + Negative agglutination with A and B cells
190
What is the typical reaction pattern for blood group O in forward and reverse typing
Negative anti-A + Negative anti-B + Positive agglutination with A and B cells
191
What are the three main categories of ABO discrepancy
Clerical error + Technical error + Clinical discrepancy
192
What is a clinical discrepancy in ABO grouping
Problem with serum and red cell grouping
193
What is the purpose of documenting results immediately in ABO testing
Prevent clerical discrepancy
194
What can happen if results are not documented right away in ABO testing
Misinterpretation + Wrong grading + Incorrect blood typing result
195
What is a common cause of clerical discrepancy when multitasking in the lab
Mixing up patient or donor worksheets
196
What is the recommended practice to avoid clerical errors when handling many samples
Test one or two patients at a time
197
What can happen if results are recorded in the wrong section of the worksheet
Clerical discrepancy
198
What is a technical discrepancy caused by inadequate washing of cells
Washed cells 3 to 4 times but over-washing can wash out antigens
199
What is the pro-zone effect in ABO testing
Too much antibody prevents lattice formation
200
What is the post-zone effect in ABO testing
Excess antigen due to incorrect cell suspension and serum ratio
201
What is the recommended ratio for red cell suspension in blood typing
2 drops anti-sera or plasma + 1 drop of 2-5 percent red cell suspension
202
What can happen if red cell suspension is too light or too heavy
Technical discrepancy
203
What can mislabeling or mixing up samples cause in ABO testing
Wrong ABO blood group result
204
What error can missed observation of hemolysis cause
Misinterpretation as no agglutination + Inaccurate result
205
What is the visual clue for hemolysis in ABO testing
Reddish supernatant
206
What is the effect of failing to add reagents in cross matching
Problem with agglutination interpretation
207
What is the effect of failing to add samples in ABO testing
Skipped serum plasma or red cell suspension
208
What is the result of using an uncalibrated centrifuge in ABO testing
Incorrect sedimentation + Affects agglutination interpretation
209
What is the effect of over-centrifugation in ABO testing
False positive reactions + Packed cells too tightly
210
What is the effect of under-centrifugation in ABO testing
False negative reactions + Dispersed red cells
211
What can contaminated reagents or dirty glassware cause in ABO testing
False positive reactions
212
What can improper shaking of tubes cause in ABO testing
False positive or false negative reactions
213
What is the recommended approach if forward and reverse typing do not match
Determine if discrepancy is in red cell or serum by observing weakest reactivity
214
What are the possible causes of weak reactions in reverse grouping
Cold reacting alloantibody + Cold reacting autoantibody + Passively acquired antibody + Rouleaux + Mismatched platelets
215
What are the possible causes of weak reactions in forward grouping
Out of group transfusion + Stem cell transplantation + Fetal-maternal bleed + A3 subgroup
216
What are the possible causes of weak reactions in both forward and reverse grouping
Cold autoantibody + Cold autoantibody and alloantibody + Out of group bone marrow or stem cell transplantation + Passively acquired antibody
217
What is the first step in resolving weak reactions in reverse grouping
Run antibody screen + Run auto control + Rule out rouleaux
218
What is the first step in resolving weak reactions in forward grouping
Run DAT + Run auto control
219
What is the first step in resolving weak reactions in both forward and reverse grouping
Wash patient cells with saline and retest + Run DAT and auto control + Run antibody screen
220
What is the first step in resolving technical errors in ABO discrepancies
Review and correct all technical factors
221
What must be done if incorrect sampling is suspected
Take a new sample and repeat testing
222
What should be used to suspend red blood cells to avoid discrepancies
Saline suspension after adequate washing
223
What causes pro-zone effect in ABO testing
Excess antibody leading to unbound immunoglobulin
224
What causes post-zone effect in ABO testing
Excess antigen causing surplus antigen binding sites
225
What is the optimal antigen-antibody ratio for ABO testing
2 volumes serum + 1 volume 2-5% red cell suspension in normal saline
226
Where does the problem lie in clinical discrepancy
Within the patient
227
What is critical in solving clinical discrepancies
Clinical history including age diagnosis transfusion history pregnancy and medication
228
What characterizes Group I ABO discrepancy
Unexpected reactions in reverse grouping due to weak or missing antibodies
229
What are common causes of Group I discrepancy
Newborns elderly leukemia immunosuppressive drugs agammaglobulinemia immunodeficiency stem cell transplants plasma exchange transfusion ABO subgroups
230
How is Group I discrepancy resolved in newborns
Only forward grouping done until 4 months of age
231
How can serum grouping reactions be enhanced in elderly patients
Incubation at room temperature for 15-30 minutes followed by centrifugation
232
What further step is taken if no reaction occurs after room temperature incubation
Incubate at 4°C for 15-30 minutes to detect cold agglutinins
233
What controls must be tested concurrently when incubating at 4°C
Auto control and O cell control
234
What should be done if centrifuge is not properly calibrated
Recalibrate to ensure proper red cell sedimentation
235
What is the effect of improper centrifugation on agglutination results
False negative if under-centrifuged false positive if over-centrifuged
236
What is the recommended procedure if discrepancy persists after washing red cells
Reinvestigate serum and forward typing and review patient history
237
What is the importance of recording ABO discrepancy results
Documentation for investigation and medicolegal evidence
238
What are common technical errors causing ABO discrepancies
Specimen mix-up inadequate washing incorrect cell suspension failure to add reagents missed hemolysis incorrect centrifugation improper interpretation
239
What is the saline replacement technique used for
Remove excess proteins causing rouleaux formation in reverse typing
240
What is rouleaux formation
Stacking of red blood cells mimicking agglutination caused by plasma abnormalities
241
What clinical conditions cause rouleaux formation
Hypergammaglobulinemia hyperfibrinogenemia plasma expanders like dextran
242
What is the importance of reviewing patient medical history in ABO discrepancy
Identify clinical causes affecting antigen or antibody expression
243
What is the procedure if ABO discrepancy cannot be resolved
Report as “ABO cannot be determined” and prepare group O red cells and group AB plasma for transfusion
244
What is the presence of two cell populations in a single individual
chimerism
245
What is the typical reaction seen in chimerism
mixed field reaction
246
What is the term for weak or missing antibodies causing unexpected reverse grouping reactions
Group 1 discrepancy
247
What is a common cause of Group 1 discrepancy in newborns
undeveloped ABO antibody production
248
What is a common cause of Group 1 discrepancy in elderly patients
depressed antibody production
249
What is a cause of Group 1 discrepancy related to immune system suppression
immunosuppressive drugs
250
What is the recommended incubation temperature to detect cold agglutinins
4 degrees Celsius
251
What is the test performed concurrently to incubation at 4 degrees Celsius to confirm cold agglutinins
autocontrol test
252
What is the term for stacking of red blood cells mimicking agglutination
rouleaux formation
253
What is the cause of pro-zone effect in ABO testing
excess antibody preventing lattice formation
254
What is the cause of post-zone effect in ABO testing
excess antigen causing surplus binding sites
255
What is the optimal ratio of serum to red cell suspension for antigen-antibody reaction
2 volumes serum + 1 volume 2-5% red cell suspension
256
What is the main cause of clerical discrepancy in ABO grouping
errors in recording or labeling results
257
What is the main cause of technical discrepancy in ABO grouping
inadequate washing + incorrect cell suspension + missed hemolysis + centrifuge errors
258
What is the clinical discrepancy in ABO grouping
problem lies within the patient’s serum or red cells
259
What are examples of clinical factors causing ABO discrepancies
leukemia + immunosuppressive therapy + bone marrow transplant + plasma exchange
260
What is the gold standard method for ABO blood grouping
test tube method
261
What is the importance of forward and reverse typing in ABO grouping
confirm ABO group and detect discrepancies
262
What is the proper way to examine agglutination in the tube method
hold tube upright and slightly tilted
263
What can vigorous shaking during agglutination cause
destruction of agglutination + mixed field reactions
264
What is the significance of documenting ABO grouping results
avoid clerical errors + provide medicolegal evidence
265
What is the term for false positive agglutination due to contaminated reagents or dirty glassware
technical discrepancy
266
What is the effect of over-centrifugation in ABO testing
false positive reactions due to tightly packed cells
267
What is the effect of under-centrifugation in ABO testing
false negative reactions due to dispersed cells
