Challenge your understanding of the ABO Blood Group System with this mock test designed for Medical Laboratory Students and Professionals. This test focuses on the genetics, antigenic makeup, and serologic testing that form the foundation of blood group identification in transfusion medicine.
Each question is based on the ASCP BOC 7th Edition (Blood Banking) and helps evaluate your ability to recognize ABO discrepancies, interpret grouping results, and understand clinical correlations.
What This Mock Test Covers ABO antigens and antibodies Forward and reverse grouping techniques Subgroups (A₁, A₂, etc.) Testing discrepancies and troubleshooting Clinical significance of ABO incompatibility
Report a question
ASCP MLS Exam MCQs Chapter 57
Why Take This Mock Test? Strengthens exam confidence Highlights areas for improvement Provides practice with clinically relevant scenarios This mock test (60 MCQs (4361 – 4420) ) is part of our ongoing ASCP MLS Exam Practice Series , giving you structured preparation for all major immunology topics.
Our Blood Banking – The ABO Blood Group System Mock Test is specifically designed for candidates appearing in ASCP MLS, AMT MLT/MT, AIMS, CSMLS, IBMS, HAAD/DOH, DHA, and MOH exams. This mock test mirrors the structure, difficulty level, and question style you can expect in the actual examination.
Take this test to: ✅ Strengthen your Pathology exam preparation. ✅ Boost confidence before the ASCP MLS Exam .
Who Should Use This Mock Test? Medical Laboratory Scientists and Technicians
Pathology Students
Professionals preparing for international laboratory certification exams
Anyone seeking to strengthen their knowledge of Blood Banking – The ABO Blood Group System
How to Use This Mock Test Effectively Simulate Exam Conditions: Attempt the test in one sitting without referring to notes.
Track Your Time: Keep within the allotted time limit to build speed.
Review Explanations: Study the answer explanations to strengthen understanding.
Repeat for Retention: Re-attempt after revision to measure improvement.
1 / 60
Category:
ASCP Exam Questions
A patient with multiple myeloma has rouleaux formation interfering with reverse typing. What technique can resolve this discrepancy?
In multiple myeloma , excess plasma proteins cause rouleaux formation , leading to false agglutination in reverse typing. Performing a saline replacement (removing the patient’s serum and replacing it with saline) disperses the rouleaux, allowing true agglutination reactions to be accurately observed.
The other options are for different problems:
a) Cold autoadsorption: Removes cold autoantibodies from the patient’s serum.
c) Enzyme treatment: Enhances the reactivity of some antibodies (like in the panel) but doesn’t resolve rouleaux in reverse typing.
d) DTT: Destroys IgM antibodies to identify IgG antibodies; doesn’t address protein-related stacking.
2 / 60
Category:
ASCP Exam Questions
What antigens would be found in the saliva of an individual with the genotype Sese Lele AO HH ?
Let’s break down the genotype Sese Lele AO HH :
HH → normal H antigen production.
AO → A antigen will be produced in secretors.
Sese → heterozygous for secretor gene → Se present → Secretor positive (H and A antigens in saliva).
Lele → heterozygous for Lewis gene → Le present → can make Lea and Leb .
In a Secretor (Se+) :
H, A in saliva (due to Se).
Lewis: since Se is present, most Le(a–b+) phenotype, so Leb in saliva (and trace Lea possible, but Leb dominates).
Thus saliva contains: Leb, A, H .
4 / 60
Category:
ASCP Exam Questions
Which of the following lectins is used to differentiate between A1 and A2 subgroups?
The lectin Dolichos biflorus specifically agglutinates A₁ cells but does not react with A₂ cells . Therefore, it is used to differentiate between A₁ and A₂ subgroups of blood group A.
Ulex europaeus → reacts with H antigen , useful for identifying group O or Bombay phenotype .
Arachis hypogaea (peanut lectin) → reacts with T antigen , not used in ABO typing.
Vicia graminea → agglutinates A₁, A₂, and some A₃ cells , but is not specific for differentiating A₁ from A₂.
5 / 60
Category:
ASCP Exam Questions
Which of the following genes must be inherited for an individual to be a secretor of ABH antigens in their saliva?
To be a secretor of ABH antigens in saliva, an individual must inherit:
At least one H (FUT1) gene to produce the H antigen on red blood cells and tissues.
At least one Se (FUT2) gene. The Se gene codes for a fucosyltransferase that adds fucose to a precursor substance in body fluids like saliva, creating soluble H antigen. This soluble H substance can then be converted to A or B antigens if the corresponding gene is present.
H only: Allows for ABH on red cells but not in secretions (non-secretor).
Se only: Is insufficient without the H gene to make the precursor structure.
Le and Se: The Lewis (Le) gene is responsible for creating Lewis antigens in secretions, but secretor status is independently determined by the Se gene in conjunction with the H gene.
6 / 60
Category:
ASCP Exam Questions
Which antigen is present in group O individuals?
The H antigen is the precursor on red blood cells from which A and B antigens are formed. All people (except those with the Bombay phenotype ) have H antigen on their red cells.
Incorrect options: a) A antigen: Present only in group A and AB .
b) B antigen: Present only in group B and AB .
d) No antigen: Incorrect — group O has H antigen .
7 / 60
Category:
ASCP Exam Questions
The immunodominant sugar responsible for blood group A specificity is:
The ABO blood group system is determined by the presence of specific sugars on red blood cells.
Blood Group A has the N-acetylgalactosamine sugar attached to the core structure.
Blood Group B has the galactose sugar.
Fucose is the foundational sugar present in all ABO groups (O, A, and B).
N-acetylglucosamine is a component of the core oligosaccharide chain but is not the immunodominant sugar for type A.
8 / 60
Category:
ASCP Exam Questions
ABO-hemolytic disease of the newborn differs from Rh HDFN in that:
a) Rh HDFN is clinically more severe than ABO HDFN
✓ True — ABO HDN is usually mild; Rh HDN can cause severe anemia/hydrops.
b) The direct antiglobulin test is weaker in Rh HDFN than ABO HDFN
✗ False — DAT is typically stronger in Rh HDN; in ABO HDN it’s often weak/mixed-field.
c) Rh HDFN occurs in the first pregnancy
✗ False — Rh HDN usually requires sensitization from a previous pregnancy.
d) The mother’s antibody screen is positive in ABO HDFN
✗ False — In ABO HDN, the antibody screen is often negative because anti-A/B are naturally occurring and not IgG in all cases; only IgG causes HDN, but screen isn’t usually positive unless other antibodies are present.
10 / 60
Category:
ASCP Exam Questions
Which of the following ABO subgroups is characterized by mixed-field agglutination with anti-A and anti-A,B?
Mixed-field agglutination (small agglutinates mixed with free cells) is characteristic of the A₃ subgroup.
A₁ and A₂ : show uniform agglutination.
Aₓ : very weak or no agglutination with anti-A, but may adsorb and elute anti-A.
A₃ : mixed-field pattern with anti-A and anti-A,B.
11 / 60
Category:
ASCP Exam Questions
A patient’s ABO typing shows 4+ reactions with anti-A and anti-B, but no reaction with A1 or B cells in the reverse type. What is the most likely cause?
In this case, the forward typing shows clear AB antigens (4+ with anti-A and anti-B) , but the reverse typing shows no reaction with A₁ or B cells—meaning no ABO antibodies are detected. This happens when the patient has low or absent immunoglobulins , such as in hypogammaglobulinemia , leading to a lack of naturally occurring anti-A or anti-B antibodies in the serum.
The other options are incorrect because:
a) Acquired B: Would show a weak or mixed field reaction with anti-B, not a 4+ reaction. The reverse type would be normal (no anti-B).
b) Cold autoantibody: Would typically cause panagglutination (false-positive reactions) in the forward type and unexpected reactions in the reverse type, not the clean, specific pattern seen here.
d) A<sub> x</sub> subgroup: Would show a weak reaction with anti-A in the forward type, not a 4+ reaction.
12 / 60
Category:
ASCP Exam Questions
What do the Oh (Classical Bombay), group O, and Lu(a-b-) phenotypes have in common?
All three phenotypes — O<sub>h</sub> (Bombay) , group O , and Lu(a–b–) — arise due to homozygosity for recessive alleles of autosomal genes that prevent normal antigen expression.
Incorrect options: a) Identical sex-linked dominant genes: Not sex-linked.
b) Identical sex-linked recessive genes: None are on sex chromosomes.
c) Identical autosomal dominant genes: Require two recessive alleles, not one dominant.
14 / 60
Category:
ASCP Exam Questions
The A₂ phenotype differs from A₁ because A₂ cells:
The A₂ phenotype is a subgroup of A that differs from A₁ primarily in the quantity and structure of A antigens on the red blood cell (RBC) surface.
Incorrect options: b) Lack the H antigen: ❌ A₂ cells actually have more H antigen , not less.
c) Are strongly reactive with anti-A₁: ❌ A₂ cells do not react with anti-A₁.
d) Have more A antigen sites: ❌ A₂ has fewer , not more, A antigen sites.
15 / 60
Category:
ASCP Exam Questions
The “H” antigen serves as a:
The H antigen is a carbohydrate chain found on red blood cells in people of all blood types. The ABO genes code for enzymes that modify this H antigen:
The A gene adds an N-acetylgalactosamine sugar to the H antigen, creating the A antigen .
The B gene adds a galactose sugar to the H antigen, creating the B antigen .
The O gene is inactive and makes no modification, leaving the H antigen unchanged, which is then identified as the O blood type .
17 / 60
Category:
ASCP Exam Questions
The A₃ subgroup is characterized by:
A₃ is one of the rare weak subgroups of A . It shows very weak expression of the A antigen on red cells — less than A₂ , but not completely absent.
Analysis of the other options:
b) No reaction with anti-A or anti-B: This describes the Bombay (Oₕ) phenotype, not A₃.
c) Strong reaction with both anti-A and anti-B: This describes the standard AB blood group phenotype.
d) Agglutination with anti-H only: This describes the Group O phenotype, which has no A or B antigens and therefore has a high concentration of H antigen.
19 / 60
Category:
ASCP Exam Questions
Group AB individuals can receive blood from:
In the ABO blood group system , transfusion compatibility depends on the antibodies present in the recipient’s plasma and the antigens on donor red cells .
Incorrect options: a) Only group O: Too restrictive; AB can receive from A, B, AB, and O.
c) Group A and B only: AB can also receive from O.
d) Group O and AB only: Missing A and B donors; incomplete.
20 / 60
Category:
ASCP Exam Questions
ABO antibodies usually appear in the serum:
At birth (a): Newborns have very low levels of ABO antibodies. The antibodies they have are primarily IgG antibodies that have been passively transferred from the mother across the placenta.
Within the first few weeks of life (b): This is the correct answer. As infants are exposed to ABO-like antigens from food, bacteria, and other environmental sources, their immune systems begin to produce their own IgM anti-A and/or anti-B antibodies. These antibodies typically reach detectable levels by 3-6 months of age.
During the fetal stage (c): The production of ABO antibodies does not occur in the fetus. The immune system is not sufficiently stimulated or developed to produce them at this stage.
Only after transfusion (d): This is incorrect. While a transfusion can strongly boost antibody levels, the natural ABO antibodies appear without any exposure to foreign red blood cells.
21 / 60
Category:
ASCP Exam Questions
Which of the following is a characteristic of the A2 phenotype?
A2 phenotype characteristics:
Weaker expression of A antigen than A1 → cells react weakly with anti-A,B ✅
Serum may contain anti-A1 , but not always → so “always contains anti-A1” ❌
Dolichos biflorus lectin reacts with A1 only , so A2 cells do not react ✅
Most common A subgroup → A1 is most common (~80%), A2 ~20% ❌
Both a and c are correct statements, but the defining feature is the weak reaction with anti-A,B .
23 / 60
Category:
ASCP Exam Questions
A person with genotype AO will have which phenotype?
In the ABO blood group system, the A and B alleles are codominant , and the O allele is recessive .
The A allele instructs the cell to produce A antigens.
The B allele instructs the cell to produce B antigens.
The O allele produces no antigen.
A person with the AO genotype has one A allele and one O allele.
The A allele is expressed, leading to the production of A antigens on the red blood cells.
The O allele is recessive and does not produce an antigen.
26 / 60
Category:
ASCP Exam Questions
H antigen is the immunodominant precursor for A and B antigens. In which individuals is H antigen found in its highest concentration on red blood cells?
The H antigen is the base structure (precursor) from which the A and B antigens are formed on red blood cells (RBCs).
Incorrect options: a) Group A₁: Most H converted → least H left .
b) Group A₂: Intermediate H level.
c) Group B: Moderate H level.
27 / 60
Category:
ASCP Exam Questions
A patient’s sample shows agglutination with anti-A and anti-B, but no reaction with A1 cells and weak reaction with B cells. The direct antiglobulin test is negative. This discrepancy is most likely due to:
Forward typing suggests group AB (reacts with anti-A and anti-B).
Reverse typing is abnormal: no reaction with A1 cells (should have anti-B if truly AB) and weak reaction with B cells.
This pattern is characteristic of a weak A subgroup (e.g., A<sub> x</sub> or A<sub> el</sub> ), where:
The A antigen is very weak (may react with some potent anti-A reagents).
The individual produces anti-A1 in their serum, which reacts with A1 cells but not with their own weak A RBCs.
The weak reaction with B cells may be due to the anti-A1 being weak or due to another factor.
28 / 60
Category:
ASCP Exam Questions
Mixed-field agglutination in ABO testing may indicate:
Mixed-field agglutination (or “mixed-field reactivity”) is characterized by the presence of two distinct populations of red blood cells in a single test sample: one population that is agglutinated and one that is not. This is a critical observation in the blood bank.
Here’s why the other options are less accurate:
a) Polyagglutination: While some forms of polyagglutination (like T-activation) can cause mixed-field agglutination, it is not the most common cause. Polyagglutination is a specific phenomenon where red cells are agglutinated by most normal adult sera. “Recent transfusion” is a far more frequent and classic cause of mixed-field agglutination in routine testing.
c) Weak subgroup of B: Weak subgroups (e.g., A<sub> x</sub> , A<sub> m</sub> ) typically cause weak or delayed agglutination overall, not a clear mixed-field pattern with two distinct cell populations.
d) Clerical error only: This is incorrect. While a clerical error (e.g., mislabeling) could theoretically lead to a mixed-field result, it is not the intrinsic cause.
32 / 60
Category:
ASCP Exam Questions
The presence of anti-A and anti-B antibodies in serum indicates which blood group?
In the ABO blood group system , the antigens present on red blood cells (RBCs) determine which antibodies are found in the serum . Antibodies are always against the antigens that the person does not have .
Incorrect options: a) Group A: Has anti-B only.
b) Group B: Has anti-A only.
c) Group AB: Has no antibodies (both A and B antigens are self).
33 / 60
Category:
ASCP Exam Questions
The A₁ antigen reacts with:
The A₁ antigen is a subtype of the A antigen found on red blood cells of most individuals with blood group A or AB. It reacts with both anti-A (which detects all A antigens) and anti-A₁ (which specifically detects the A₁ subtype).
Incorrect options: b) Anti-B and anti-A: A₁ cells do not react with anti-B (they have no B antigen).
c) Anti-H only: A₁ cells have less H antigen , not “only” H antigen.
d) Anti-A₂ and anti-B: There is no reagent called anti-A₂ , and A₁ cells lack B antigen.
34 / 60
Category:
ASCP Exam Questions
A patient’s red blood cells type as 4+ with anti-A, 0 with anti-B, and 4+ with anti-A,B. The serum reacts 0 with A1 cells and 4+ with B cells. What is the patient’s ABO group?
Let’s break this down:
This is a classic group A pattern:
A antigen on red cells.
Anti-B in serum.
37 / 60
Category:
ASCP Exam Questions
Which lectin is used to differentiate between A₁ and A₂ cells?
Lectins are plant extracts that act like antibodies by agglutinating specific red cell antigens. In ABO grouping, certain lectins are used to differentiate subgroups based on antigen specificity.
Here is the role of the other lectins listed:
b) Ulex europaeus : This lectin is specific for the H antigen . It is used to identify Group O cells, which have the highest concentration of H substance.
c) Phaseolus vulgaris : This is the lectin from the kidney bean. It is anti-B but is not commonly used in routine blood grouping to differentiate subgroups of B.
d) Vicia graminea : This lectin is specific for the N antigen of the MNS blood group system, not the ABO system.
39 / 60
Category:
ASCP Exam Questions
The phenomenon of “acquired B” antigen can occur in:
The “acquired B” phenomenon is a rare, transient condition in which group A₁ red cells appear to react weakly with anti-B serum , even though the person genetically lacks the B antigen .
Incorrect options: b) Iron deficiency anemia: Affects RBC morphology, not ABO antigens.
c) Vitamin B₁₂ deficiency: Causes megaloblastic changes, no antigen alteration.
d) Plasma protein disorders: Affect plasma viscosity, not RBC antigen structure.
40 / 60
Category:
ASCP Exam Questions
ABO hemolytic disease of the newborn:
Group O mothers naturally have IgG anti-A and anti-B antibodies that can cross the placenta.
Mothers who are group A or B typically have IgM antibodies that do not cross the placenta.
Therefore, ABO HDN almost exclusively occurs when a group O mother has a baby with a different blood group (A or B).
The other options are incorrect:
a) It is usually mild and rarely requires exchange transfusion.
b) It can occur in a first-born child, unlike Rh disease.
c) It is rarely severe enough to cause stillbirth.
42 / 60
Category:
ASCP Exam Questions
For a patient with the Bombay phenotype (Oh ), what is the only safe source of Red Blood Cells for transfusion?
Individuals with the Bombay (Oₕ) phenotype lack the H antigen, which is the precursor for the A and B antigens.
Their serum contains potent anti-H , in addition to anti-A and anti-B.
Since all other blood groups (O, A, B, AB) express the H antigen , transfusing any of them would cause a severe hemolytic transfusion reaction.
The only compatible red blood cells are from another Bombay phenotype donor , as these cells also lack the H antigen and will not be attacked by the patient’s anti-H.
46 / 60
Category:
ASCP Exam Questions
Which method detects ABO antibodies in serum or plasma?
Here’s why the other options are incorrect:
a) Forward grouping: This is the opposite test. It detects ABO antigens on a person’s own red blood cells.
c) Crossmatching: This is a pre-transfusion test designed to check for compatibility between a specific donor’s red cells and a specific recipient’s serum. While it detects antibodies, its purpose is broader than just identifying ABO type.
d) DAT (Direct Antiglobulin Test): This test detects antibodies or complement proteins that are already bound to a person’s red blood cells inside the body .
47 / 60
Category:
ASCP Exam Questions
Reverse grouping discrepancies may be due to:
In reverse ABO grouping , the patient’s serum (plasma) is tested against known reagent red cells (A₁ and B cells) to detect naturally occurring antibodies (anti-A or anti-B). A discrepancy occurs when the serum reactions don’t match the expected pattern based on the cell (forward) grouping .
Incorrect options: b) Lack of H antigen: Associated with Bombay phenotype , affects forward grouping , not reverse.
c) Weak D antigen: Involves Rh typing , not ABO discrepancies.
d) Bacterial contamination: Can cause hemolysis or unexpected reactions, but not a classic cause of reverse grouping discrepancy.
48 / 60
Category:
ASCP Exam Questions
A group A, Rh-positive infant of a group O, Rh-positive mother has a weakly positive direct antiglobulin test and a moderately elevated bilirubin 12 hours after birth. The most likely cause is:
When a group O, Rh-positive mother gives birth to a group A, Rh-positive infant , the mother’s IgG anti-A (and possibly anti-B) antibodies can cross the placenta and attach to the baby’s A red blood cells .
This causes a positive direct antiglobulin test (DAT) and mild to moderate hemolysis , resulting in elevated bilirubin levels soon after birth.
Key points:
ABO hemolytic disease often occurs in first pregnancies , unlike Rh incompatibility, which typically affects subsequent pregnancies.
The hemolysis is usually mild , rarely requiring exchange transfusion.
Rh incompatibility is ruled out because both mother and infant are Rh-positive
49 / 60
Category:
ASCP Exam Questions
The fundamental principle of ABO typing involves:
ABO blood grouping is based on:
Forward typing: Testing the patient’s red blood cells with known anti-A and anti-B reagents to detect A and B antigens.
Reverse typing: Testing the patient’s serum with known A₁ and B red cells to detect the expected anti-A and/or anti-B antibodies.
This dual testing confirms the ABO group by identifying both the antigens on RBCs and the naturally occurring antibodies in the plasma.
51 / 60
Category:
ASCP Exam Questions
Individuals with the Bombay phenotype will type as:
The Bombay phenotype (Oh) is a rare blood group that lacks the H antigen , which is the precursor for A and B antigens .
Analysis of the other options:
b) AB group with weak reactivity: Incorrect. They have no A or B antigens, so they cannot be AB.
c) B group with anti-A: Incorrect. They have no B antigen and their serum contains anti-B in addition to anti-A and anti-H.
d) A₂ group with no anti-H: Incorrect. They are not group A, and crucially, they have a very strong anti-H in their serum.
52 / 60
Category:
ASCP Exam Questions
Which method is used to detect ABO antigens on red cells?
Here is a breakdown of the other terms:
a) Reverse grouping: This is the method used to detect ABO antibodies in an individual’s serum . It involves testing the person’s serum with known commercial red cells (A1 cells, B cells) to confirm the presence of the expected antibodies.
c) Coagulation test: This is unrelated to blood grouping. It is a test used to measure the blood’s ability to clot (e.g., PT, PTT).
d) Antiglobulin test: This is a different test, also known as the Coombs test. It is used to detect antibodies that are coating red blood cells but do not directly cause agglutination.
53 / 60
Category:
ASCP Exam Questions
When preparing units for an exchange transfusion for an infant with ABO HDFN, which of the following units should be selected if the infant is group A and the mother is group O?
Key principles for selecting units in ABO HDFN:
RBCs should lack the antigen that maternal antibodies target → maternal anti-A is in plasma, so ideally RBCs should not express A antigen .
Plasma should not contain antibodies that can attack infant RBCs → AB plasma is “universal” (no anti-A or anti-B).
Rh compatibility : use Rh-negative if infant is not typed yet or at risk.
Options:
a) Group A, Rh-positive RBCs → wrong, would be attacked by maternal anti-A.
b) Group O, Rh-positive RBCs → safer, RBCs lack A/B antigens, but plasma may contain anti-A (risk).
c) Group O, Rh-negative RBCs suspended in group AB plasma → ✅ correct: RBCs lack A/B (safe from maternal anti-A), AB plasma has no anti-A/B (safe for infant).
d) Group A, Rh-positive RBCs suspended in AB plasma → RBCs still have A antigen → risk.
54 / 60
Category:
ASCP Exam Questions
Which reagent is used to identify H antigen expression?
Ulex europaeus lectin, extracted from gorse seeds, is the specific reagent used to identify H antigen expression on red blood cells. It binds to the terminal sugar (L-fucose) that defines the H antigen.
Analysis of the other options:
a) Dolichos biflorus lectin: This is used to identify the A₁ antigen, not the H antigen.
c) A₁ cells: These are used in reverse grouping to detect the presence of anti-A₁ antibody in a patient’s serum. They are not a reagent for detecting antigens on cells.
d) Anti-D reagent: This is used to determine the Rh(D) blood type, which is completely separate from the ABO and H systems.
56 / 60
Category:
ASCP Exam Questions
Which of the following is a subgroup of A with weaker antigen expression?
In the ABO blood group system, the most important and common subgroup is the division of blood group A into A₁ and A₂ .
A₁ (a): This is the most common and strongly expressed A antigen. Approximately 80% of group A or AB individuals are A₁.
A₂ (b): This is the most common subgroup of A, characterized by weaker antigen expression compared to A₁. About 20% of group A or AB individuals are A₂. The number of A antigen sites on A₂ red cells is significantly lower than on A₁ cells.
B₃ (c): This is not a standard or recognized subgroup in the ABO system.
AB (d): This is a separate phenotype, not a subgroup of A.
57 / 60
Category:
ASCP Exam Questions
In a group O individual with Le and Se genes, what ABH and Le antigens are present in their secretions?
Group O means they have H antigen (but not A or B).
Se gene (FUT2) allows H antigen to be secreted into body fluids.
Le gene (FUT3) converts secreted H antigen into Leb antigen.
A small amount of unconverted H antigen remains, and a trace of Lea may be present, but the dominant antigens in secretions are Leb and H .
In a group O, Le, Se individual, Leb is the major Lewis antigen in secretions, and H substance is also present.
58 / 60
Category:
ASCP Exam Questions
In ABO typing, hemolysis after adding anti-A serum indicates:
In ABO blood typing , the presence of agglutination or hemolysis after adding an antisera (like Anti-A or Anti-B ) indicates a positive antigen–antibody reaction .
Analysis of the other options:
a) Strong antibody presence: While hemolysis requires a strong reaction, this option is less precise. The key takeaway is that it signifies a positive reaction , not just the presence of a strong antibody.
c) Test invalidity: This is incorrect. Hemolysis is a valid, expected, and interpretable result in tube-based ABO typing. It does not invalidate the test; it provides a positive result.
d) Protein degradation: This is unrelated. Degraded reagents would more likely lead to weak or false-negative reactions, not hemolysis.
59 / 60
Category:
ASCP Exam Questions
A discrepancy between forward and reverse grouping may be caused by:
In ABO blood grouping , two types of tests are performed:
Forward grouping (cell grouping): Patient’s RBCs are tested with known antisera (Anti-A, Anti-B) .
Reverse grouping (serum grouping): Patient’s serum is tested with known reagent RBCs (A cells, B cells) .
Other options (incorrect): a) Incorrect centrifugation speed: May affect strength of agglutination but usually does not cause forward/reverse discrepancy specifically.
c) Excess plasma volume: May cause rouleaux formation or non-specific reactions, but not a typical cause of ABO discrepancy.
d) Use of outdated reagents: Can cause weak or false reactions , but this affects both forward and reverse reactions uniformly — not necessarily a discrepancy between them.
60 / 60
Category:
ASCP Exam Questions
Which of the following forward and reverse ABO typing results is typical for an Ax subgroup?
The A<sub> x</sub> subgroup is characterized by very weak expression of the A antigen on red blood cells.
Forward Typing (Cells):
Weak with anti-A: The A antigen is present but in very low numbers, leading to weak or negative agglutination with routine anti-A reagent.
0 with anti-B: The B antigen is absent.
Reverse Typing (Serum):
0 with A<sub> 1</sub> cells: The patient’s serum contains anti-A<sub> 1</sub> antibody, which agglutinates common A<sub> 1</sub> cells. This is the key serological clue.
4+ with B cells: The serum contains the expected anti-B antibody.
Your score is
The average score is 45%
Follow us on Sicial Media:
Restart quiz
Top 8 Medical Laboratory Scientist (MLS) Exams: Top 8 Medical Laboratory Scientist (MLS) Exams that are recognized globally and can help professionals validate their credentials and enhance their career opportunities:
1. ASCP – American Society for Clinical Pathology (USA) Exam Name: MLS(ASCP)Eligibility: Bachelor’s degree with clinical laboratory experience.Global Recognition: HighPurpose: Certifies Medical Laboratory Scientists in the United States and internationally.2. AMT – American Medical Technologists (USA) Exam Name: MLT(AMT) or MT(AMT)Eligibility: Academic and/or work experience in medical laboratory technology.Global Recognition: ModeratePurpose: Credentialing for medical technologists and technicians.3. AIMS – Australian Institute of Medical and Clinical Scientists Exam Name: AIMS Certification ExamEligibility: Assessment of qualifications and work experience.Recognition: Required for practice in Australia.Purpose: Certification and registration in Australia.4. CSMLS – Canadian Society for Medical Laboratory Science Exam Name: CSMLS General or Subject-specific ExamsEligibility: Graduation from a CSMLS-accredited program or equivalent.Recognition: CanadaPurpose: Entry-to-practice certification in Canada.5. IBMS – Institute of Biomedical Science (UK) Exam Name: Registration and Specialist Portfolio AssessmentEligibility: Accredited degree and lab experience.Recognition: UK and some Commonwealth countries.Purpose: Biomedical Scientist registration with the HCPC (UK).6. HAAD / DOH – Department of Health, Abu Dhabi (UAE) Exam Name: DOH/HAAD License ExamEligibility: Degree in medical laboratory science and experience.Recognition: UAE (Abu Dhabi)Purpose: Licensure for medical laboratory practice in Abu Dhabi.7. DHA – Dubai Health Authority (UAE) Exam Name: DHA License Exam for Medical Laboratory TechnologistsEligibility: Relevant degree and experience.Recognition: Dubai, UAEPurpose: Professional license for clinical laboratory practice in Dubai.8. MOH – Ministry of Health (Gulf Countries like UAE, Saudi Arabia, Kuwait) Exam Name: MOH License ExamEligibility: BSc/Diploma in Medical Laboratory + experience.Recognition: Varies by country.Purpose: Required for practicing in public and private sector labs.Tags: #ASCPMLS #MLSexam #LabTech #MedicalLaboratory #BOCexam #FreePracticeQuestions #QualityControl #LaboratorySafety
Possible References Used
⚠️ Disclaimer: The content on LabTestsGuide.com is for informational and educational purposes only . We do not guarantee the accuracy, completeness, or timeliness of the information provided. Always consult qualified healthcare professionals for medical advice, diagnosis, or treatment. LabTestsGuide.com is not liable for any decisions made based on the information on this site.
ASCP
American Society for Clinical Pathology (USA)
AMT
American Medical Technologists (USA)
AIMS
Australian Institute of Medical and Clinical Scientists
CSMLS
Canadian Society for Medical Laboratory Science
IBMS
Institute of Biomedical Science (UK)
HAAD
Health Authority - Abu Dhabi
MOH
Ministry of Health (UAE)
DHA
Dubai Health Authority
Comprehensive question bank with Answer Key and Mock Test
Performance analytics and get Mock Test Certificate
Mobile-friendly interface for on-the-go studying
Timed mock exams that simulate real test conditions