The immunodominant sugar of the A antigen is:
Show answer
Answer: A — N-acetylgalactosamine
B antigen = D-galactose; H antigen = L-fucose. The H antigen is the precursor for A and B.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Exam Prep
Blood Bank practice questions.
ABO, Rh and other blood groups, compatibility testing, components, donor selection, transfusion reactions and HDFN.
Independent practice questions written by Labologics. Not affiliated with DHA, DOH (formerly HAAD), SCFHS, Prometric or any exam body. Not recalled exam questions.
ABO system
The H antigen's immunodominant sugar is:
Show answer
Answer: B — L-fucose
Group O red cells have the most H antigen; A1B cells have the least.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Red cells that lack A, B and H antigens, with anti-A, anti-B and anti-H in the serum, indicate:
Show answer
Answer: C — Bombay phenotype (Oh)
Bombay patients can receive only Bombay blood because their anti-H reacts with group O cells.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Naturally occurring ABO antibodies are mainly of class:
Show answer
Answer: D — IgM
They react at room temperature and can activate complement, causing intravascular hemolysis in ABO-incompatible transfusion. Group O people also have IgG anti-A,B.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Parents with blood groups AB and A can have children of which groups?
Show answer
Answer: A — A, B or AB
An AB parent always passes A or B, so the child cannot be group O.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Forward grouping is group O, but reverse grouping shows no anti-A or anti-B in an elderly patient. The most likely cause is:
Show answer
Answer: B — Weak or missing antibodies due to age or hypogammaglobulinemia
Newborns (under 4-6 months) also lack ABO antibodies, so reverse grouping is not done on them.
Reference: AABB Technical Manual
Extra reactions in reverse grouping in a patient with multiple myeloma are most likely due to:
Show answer
Answer: C — Rouleaux formation
Saline replacement disperses rouleaux; true agglutination remains.
Reference: AABB Technical Manual
Anti-A1 lectin (Dolichos biflorus) is used to distinguish:
Show answer
Answer: D — A1 from A2
Ulex europaeus lectin detects H antigen.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Secretor status (ABH substances in saliva) is controlled by the gene:
Show answer
Answer: A — Se (FUT2)
About 80% of people are secretors.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Rh system
The most immunogenic red cell antigen after A and B is:
Show answer
Answer: B — D
D-negative patients should get D-negative red cells, especially girls and women of childbearing age.
Reference: AABB Technical Manual
In Wiener notation, R1 corresponds to the Fisher-Race haplotype:
Show answer
Answer: C — DCe
R2 = DcE, r = dce, r' = dCe, r'' = dcE, R0 = Dce.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
The genotype r'r in Fisher-Race notation is:
Show answer
Answer: D — dCe/dce
r' (dCe) and r (dce) both lack D, so r'r is D negative.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
A father is R1R1 and the mother is R1r. Possible genotypes of their children are:
Show answer
Answer: A — R1R1 or R1r
The father always passes R1; the mother passes R1 or r.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Which phenotype shows the strongest D antigen expression?
Show answer
Answer: B — R2R2 (and especially D--)
Fewer C/c and E/e antigens leave more D sites; D-- has exalted D expression.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Weak D testing uses an indirect antiglobulin phase mainly for:
Show answer
Answer: C — Donors, so weakly expressed D is not labeled D negative
Policies for patients vary; many labs treat weak D patients as D negative or use RHD genotyping.
Reference: AABB Technical Manual
Other blood groups
Regarding Kell antigens, which is correct?
Show answer
Answer: D — K is low-prevalence (about 9%) and k is high-prevalence (about 99.8%)
Anti-K is clinically significant and can cause severe HDFN by suppressing red cell production.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
The Fy(a-b-) phenotype, common in people of West African descent, gives resistance to:
Show answer
Answer: A — Plasmodium vivax
The Duffy glycoprotein is a receptor for P. vivax.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Which antibodies are well known for delayed hemolytic transfusion reactions because they fall to undetectable levels?
Show answer
Answer: B — Anti-Jka and anti-Jkb (Kidd)
Kidd antibodies show dosage and bind complement.
Reference: AABB Technical Manual
Neonatal red cells mainly carry:
Show answer
Answer: C — i antigen
i converts to I during the first two years of life.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Anti-i cold agglutinin is associated with:
Show answer
Answer: D — Infectious mononucleosis (EBV)
Anti-I is associated with Mycoplasma pneumoniae.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
A patient with anti-M (reactive at 37 C/AHG) needs red cells that are:
Show answer
Answer: A — M antigen negative and crossmatch compatible
Most anti-M is cold-reacting IgM and not clinically significant; those reacting at 37 C or AHG need antigen-negative blood.
Reference: AABB Technical Manual
Lewis antigens are unusual because they:
Show answer
Answer: B — Are adsorbed onto red cells from plasma
Lewis antibodies are usually IgM and do not cause HDFN, because Lewis antigens are poorly developed at birth.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Antiglobulin & compatibility
The direct antiglobulin test (DAT) detects:
Show answer
Answer: C — Antibody or complement bound to red cells in vivo
DAT is positive in HDFN, autoimmune hemolytic anemia and hemolytic transfusion reactions.
Reference: AABB Technical Manual
The antibody screen uses which test?
Show answer
Answer: D — Indirect antiglobulin test with group O screening cells
Screening cells are group O so ABO antibodies do not interfere.
Reference: AABB Technical Manual
Check cells (IgG-coated red cells) are added to negative AHG tubes to:
Show answer
Answer: A — Confirm the AHG reagent was active and not neutralized by unwashed serum
If check cells do not agglutinate, the test must be repeated.
Reference: AABB Technical Manual
Enzyme (e.g., ficin, papain) treatment of red cells destroys which antigens?
Show answer
Answer: B — M, N, S, Fya and Fyb
Enzymes enhance Rh, Kidd, Lewis, I and P1 reactions.
Reference: AABB Technical Manual
An immediate spin crossmatch mainly detects:
Show answer
Answer: C — ABO incompatibility
An AHG crossmatch is needed when the patient has clinically significant antibodies.
Reference: AABB Technical Manual
An O-negative patient has anti-K. The most practical source of compatible blood is:
Show answer
Answer: D — O-negative, K-negative units from the blood supply (about 91% of donors are K negative)
Because K is low-prevalence, K-negative units are easy to find. Sibling testing is used for antibodies to high-prevalence antigens.
Reference: AABB Technical Manual
Components & storage
Red cells in CPDA-1 can be stored at 1-6 C for:
Show answer
Answer: B — 35 days
Additive solutions (e.g., SAGM, AS-1) extend storage to 42 days.
Reference: AABB Technical Manual
Platelet concentrates are stored at:
Show answer
Answer: B — 20-24 C with continuous gentle agitation, usually up to 5 days
Room-temperature storage increases the risk of bacterial contamination.
Reference: AABB Technical Manual
Fresh frozen plasma stored at -18 C or colder is usable for up to:
Show answer
Answer: B — 1 year
Thawed FFP is kept at 1-6 C and used within 24 hours (or longer as thawed plasma according to local policy).
Reference: AABB Technical Manual
Cryoprecipitate is rich in:
Show answer
Answer: D — Fibrinogen, factor VIII, vWF, factor XIII and fibronectin
It is mainly used to replace fibrinogen.
Reference: AABB Technical Manual
Blood from a first-degree relative (directed donation) should be:
Show answer
Answer: A — Irradiated to prevent transfusion-associated GVHD
Related donors share HLA haplotypes, so donor lymphocytes may not be rejected.
Reference: AABB Technical Manual
Washed red cells are indicated for:
Show answer
Answer: B — IgA-deficient patients with anti-IgA and severe allergic reactions
Washing removes plasma proteins. Irradiation prevents TA-GVHD; leukoreduction reduces CMV risk.
Reference: AABB Technical Manual
During red cell storage, which change occurs?
Show answer
Answer: C — 2,3-DPG and ATP fall, and potassium in the supernatant rises
Lower 2,3-DPG increases oxygen affinity of hemoglobin.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Donor selection
A common minimum hemoglobin for whole blood donation is:
Show answer
Answer: B — 12.5 g/dL (13 g/dL for men in some programs)
Exact cut-offs vary by national policy.
Reference: WHO: Blood donor selection guidelines
The usual minimum interval between whole blood donations is:
Show answer
Answer: B — 8 weeks (56 days) or more, by national policy
Many programs use longer intervals for women.
Reference: WHO: Blood donor selection guidelines
Aspirin taken 2 days ago defers a donor from:
Show answer
Answer: B — Apheresis platelet donation (as the only platelet source)
Aspirin affects platelet function for the platelet's lifespan.
Reference: AABB Technical Manual
Which person should not donate blood?
Show answer
Answer: C — A pregnant woman
Pregnant women are deferred during pregnancy and for a period after delivery.
Reference: WHO: Blood donor selection guidelines
Transfusion reactions
The most common cause of fatal acute hemolytic transfusion reactions is:
Show answer
Answer: D — ABO-incompatible transfusion due to clerical (identification) errors
Correct patient identification at sampling and bedside is the key prevention.
Reference: AABB Technical Manual
Acute respiratory distress within 6 hours of plasma transfusion, linked to donor anti-HLA or anti-HNA antibodies, is:
Show answer
Answer: A — TRALI
TACO is circulatory overload, often with raised blood pressure and BNP.
Reference: AABB Technical Manual
Hives (urticaria) during FFP transfusion indicate:
Show answer
Answer: B — Allergic reaction to plasma proteins
Mild urticaria can be treated with antihistamines; anaphylaxis needs immediate management.
Reference: AABB Technical Manual
Febrile non-hemolytic transfusion reactions are reduced by:
Show answer
Answer: C — Pre-storage leukocyte reduction
They are caused by cytokines and anti-leukocyte antibodies.
Reference: AABB Technical Manual
HDFN
Severe hemolytic disease of the fetus and newborn is most often caused by:
Show answer
Answer: D — Anti-D (and other IgG alloantibodies such as anti-K and anti-c)
ABO HDFN is common but usually mild, because A and B antigens are weak on fetal cells.
Reference: Harmening: Modern Blood Banking & Transfusion Practices
Rh immune globulin (anti-D) is given to:
Show answer
Answer: A — D-negative mothers who are not already immunized, at 28 weeks and after delivery of a D-positive baby
The dose after delivery is adjusted using a fetal bleed test (e.g., Kleihauer-Betke or flow cytometry).
Reference: AABB Technical Manual
The Kleihauer-Betke test works because fetal hemoglobin:
Show answer
Answer: B — Resists acid elution, so fetal cells stain pink while maternal cells look like ghosts
It estimates fetal-maternal hemorrhage volume to calculate the RhIG dose.
Reference: Harmening: Modern Blood Banking & Transfusion Practices