A mixed field reaction with anti-A in a group A patient most often follows:

Transfusion of group O red cells

An antibody screen is positive with one screening cell at AHG phase and the autocontrol is negative. The next step is:

An antibody identification panel

ABO and Rh grouping, antibody screen and crossmatching

60 Lab technician recruitment practice questions on ABO and Rh grouping, antibody screen and crossmatching, part of Blood Banking and Immunohaematology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
Haemolysis in a tube during reverse grouping is read as:
1. AAn invalid sample
2. BA rouleaux effect
3. CA positive reaction
4. DA negative reaction
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Answer: C · A positive reaction
Some ABO antibodies, especially strong anti-A or anti-B in group O people, bind complement and lyse the reagent cells. Lysis means antigen and antibody have reacted, so it counts as positive. Using plasma or EDTA samples prevents complement-mediated lysis.
- A: Lysis is a valid reaction, not a reason to reject the sample.
- B: Rouleaux causes stacking, not haemolysis.
- D: Lysis shows a reaction occurred and is never negative.
Question 2 · Medium
A mixed field reaction with anti-A in a group A patient most often follows:
1. AHigh-dose vitamin B12
2. BTransfusion of group O red cells
3. CRouleaux from myeloma
4. DA cold autoantibody
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Answer: B · Transfusion of group O red cells
Mixed field means two cell populations: some agglutinated, some free. A group A patient recently given O cells shows the patient's A cells clumped and the donor O cells free. A3 subgroup and bone marrow transplant can give the same pattern.
- A: Vitamin B12 does not create two red cell populations.
- C: Rouleaux is not a mixed field pattern.
- D: A cold autoantibody agglutinates all cells, not two populations.
Question 3 · Medium
An antibody screen is positive with one screening cell at AHG phase and the autocontrol is negative. The next step is:
1. ARepeat the ABO group
2. BPerform a DAT on the donor
3. CAn antibody identification panel
4. DIssue group O blood at once
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Answer: C · An antibody identification panel
A positive screen with a negative autocontrol suggests an alloantibody. A panel of group O cells with known antigens identifies its specificity. Antigen-negative units are then chosen and crossmatched at the AHG phase.
- A: ABO grouping does not identify unexpected antibodies.
- B: A donor DAT does not explain the patient's antibody.
- D: Group O cells may still carry the antigen the antibody targets.
Question 4 · Easy
Anti-A and anti-B agglutinate saline-suspended cells directly because the antibody molecule is:
1. AHexameric
2. BMonomeric
3. CPentameric
4. DDimeric
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Answer: C · Pentameric
Naturally occurring anti-A and anti-B are chiefly IgM, made in response to A- and B-like substances in gut bacteria. IgM is pentameric and agglutinates saline-suspended cells directly at room temperature. Group O people also have some IgG anti-A,B, which can cross the placenta.
- A: Hexameric forms are not the usual ABO antibody.
- B: Monomeric IgG is too small to bridge saline-suspended cells.
- D: Dimeric IgA is a minor part of ABO antibodies.
Question 5 · Easy
Ulex europaeus lectin agglutinates most strongly the cells of group:
1. AO
2. BA1B
3. CA2B
4. DA1
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Answer: A · O
H substance is converted to A or B antigen, so group O cells, which convert none, carry the most H. The usual order is O > A2 > B > A2B > A1 > A1B. Anti-H lectin from Ulex europaeus reacts most strongly with group O cells.
- B: A1B cells have the least H of all common groups.
- C: A2B cells have much less H than group O.
- D: A1 cells convert most of their H to A antigen.
Question 6 · Medium
A positive crossmatch with a negative antibody screen most likely suggests:
1. AA cold anti-I autoantibody
2. BRouleaux formation
3. CAn anti-D in the patient
4. DAnti-Wra in the patient
Answer and explanation in LearnFree account
Question 7 · Medium
An antibody reacts with untreated panel cells but not with ficin-treated cells. It is most likely:
1. AAnti-E
2. BAnti-Jka
3. CAnti-Lea
4. DAnti-Fya
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Question 8 · Medium
In the 37 °C incubation phase of a crossmatch, the main event is:
1. ARouleaux dispersal
2. BComplement inactivation
3. CIgG antibody binding to red cells
4. DIgM agglutination of ABO cells
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Question 9 · Hard
A pregnant woman's antibody screen reacts with both screening cells at AHG, and all panel cells react except the K+k- cells. The autocontrol is negative. The likely antibody is:
1. AAnti-k (Cellano)
2. BWarm autoantibody
3. CAnti-K
4. DAnti-D
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Question 10 · Hard
A group O woman's baby is group A with a weak positive DAT, jaundice on day 1 and spherocytes. The best explanation is:
1. APhysiological jaundice
2. BHereditary spherocytosis
3. CRh HDFN from anti-D
4. DABO HDFN from maternal IgG anti-A,B
Answer and explanation in LearnFree account
Question 11 · Easy
Coombs control cells (check cells) added to a negative AHG test are red cells coated with:
1. AIgM
2. BComplement C1q
3. CAlbumin
4. DIgG
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Question 12 · Hard
Forward: anti-A 0, anti-B 0. Reverse: A1 0, B 0. Patient is 85 years old. The likely group, pending extended tests, is:
1. AAB
2. BA2 with anti-A1
3. CO with weak antibodies
4. DBombay
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Question 13 · Medium
A patient of unknown group needs plasma urgently. The group to issue is:
1. AAB plasma
2. BB plasma
3. CA plasma
4. DO plasma
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Question 14 · Hard
Forward: anti-A 4+, anti-B 1+. Reverse: A1 0, B 4+. Patient has colon cancer. The likely explanation is:
1. AGroup AB with weak anti-A
2. BRouleaux
3. CAcquired B antigen
4. DB(A) phenotype
Answer and explanation in LearnFree account
Question 15 · Medium
Saline anti-D reagent used for direct tube Rh typing is usually:
1. APolyclonal IgE
2. BMonoclonal IgM
3. CPolyclonal IgG
4. DMonoclonal IgA
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Question 16 · Medium
A falsely negative AHG result is most often due to:
1. ADirty glassware
2. BUsing cells with a positive DAT
3. COvercentrifugation
4. DInadequate washing of cells
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Question 17 · Easy
Which routine blood bank test is built on the indirect Coombs method?
1. ACord blood DAT
2. BAntibody screen
3. CForward grouping
4. DSaline tube grouping
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Question 18 · Easy
The gel card method of grouping reads a positive reaction as:
1. ACells spread evenly in the reservoir
2. BA button at the bottom of the column
3. CA pink supernatant above the gel
4. DCells trapped at the top or within the gel
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Question 19 · Easy
The lectin Dolichos biflorus is used to distinguish:
1. AO from Bombay
2. BD from weak D
3. CA1 from A2
4. DB from AB
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Question 20 · Medium
Which group must be issued if a group AB patient needs red cells and AB blood is not available?
1. AA or B red cells, then O
2. BOnly AB plasma
3. CAny group with plasma
4. DOnly O whole blood
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Question 21 · Medium
A cold autoantibody causes discrepancy in grouping. The simplest first step is to:
1. AWash cells with warm saline and retest
2. BIncubate at 4 °C
3. CAdd bovine albumin
4. DUse enzyme-treated reagent cells
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Question 22 · Easy
A blood bank picks screening cells that lack A and B antigens. Their group is:
1. AB
2. BAB
3. CA
4. DO
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Question 23 · Hard
Forward: anti-A 0, anti-B 0. Reverse: A1 4+, B 4+, O cells 4+. Autocontrol 0. The likely phenotype is:
1. AGroup O
2. BBombay (Oh)
3. CGroup A2 with anti-A1
4. DGroup O with cold autoantibody
Answer and explanation in LearnFree account
Question 24 · Hard
A patient transfused 7 days ago now has a falling haemoglobin, a positive DAT (IgG) and a new anti-Jka. This is a:
1. AAcute haemolytic transfusion reaction
2. BFebrile non-haemolytic reaction
3. CDelayed haemolytic reaction
4. DWarm autoimmune haemolytic anaemia
Answer and explanation in LearnFree account
Question 25 · Hard
A tube IAT is negative, and check cells added afterwards also fail to agglutinate. The correct action is to:
1. AAdd more AHG to the same tube
2. BRepeat the test
3. CReport the IAT as negative
4. DReport the IAT as positive
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35 more ABO and Rh grouping, antibody screen and crossmatching questions

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ABO and Rh grouping, antibody screen and crossmatching

Haemolysis in a tube during reverse grouping is read as:

A mixed field reaction with anti-A in a group A patient most often follows:

An antibody screen is positive with one screening cell at AHG phase and the autocontrol is negative. The next step is:

Anti-A and anti-B agglutinate saline-suspended cells directly because the antibody molecule is:

Ulex europaeus lectin agglutinates most strongly the cells of group:

A positive crossmatch with a negative antibody screen most likely suggests:

An antibody reacts with untreated panel cells but not with ficin-treated cells. It is most likely:

In the 37 °C incubation phase of a crossmatch, the main event is:

A pregnant woman's antibody screen reacts with both screening cells at AHG, and all panel cells react except the K+k- cells. The autocontrol is negative. The likely antibody is:

A group O woman's baby is group A with a weak positive DAT, jaundice on day 1 and spherocytes. The best explanation is:

Coombs control cells (check cells) added to a negative AHG test are red cells coated with:

Forward: anti-A 0, anti-B 0. Reverse: A1 0, B 0. Patient is 85 years old. The likely group, pending extended tests, is:

A patient of unknown group needs plasma urgently. The group to issue is:

Forward: anti-A 4+, anti-B 1+. Reverse: A1 0, B 4+. Patient has colon cancer. The likely explanation is:

Saline anti-D reagent used for direct tube Rh typing is usually:

A falsely negative AHG result is most often due to:

Which routine blood bank test is built on the indirect Coombs method?

The gel card method of grouping reads a positive reaction as:

The lectin Dolichos biflorus is used to distinguish:

Which group must be issued if a group AB patient needs red cells and AB blood is not available?

A cold autoantibody causes discrepancy in grouping. The simplest first step is to:

A blood bank picks screening cells that lack A and B antigens. Their group is:

Forward: anti-A 0, anti-B 0. Reverse: A1 4+, B 4+, O cells 4+. Autocontrol 0. The likely phenotype is:

A patient transfused 7 days ago now has a falling haemoglobin, a positive DAT (IgG) and a new anti-Jka. This is a:

A tube IAT is negative, and check cells added afterwards also fail to agglutinate. The correct action is to: