WorksheetsWeek 3
Total questions: 100
Worksheet time: 54mins
A patient presents with signs of hemolytic anemia. The DAT is positive (2+) with Polyspecific AHG. Reflex testing with Monospecific reagents reveals: Anti-IgG (Negative), Anti-C3d (2+). Which of the following clinical conditions is most consistent with this pattern?
Warm Autoimmune Hemolytic Anemia (WAIHA)
Hemolytic Disease of the Newborn (Rh incompatibility)
Cold Agglutinin Disease (CAD)
Delayed Hemolytic Transfusion Reaction due to Anti-Jk(a)
In the investigation of Drug-Induced Immune Hemolytic Anemia (DIIHA), which mechanism results in a positive DAT due to membrane modification, where plasma proteins (immunoglobulins, complement, albumin) adsorb non-specifically onto the RBC membrane?
Drug-Adsorption (Hapten) Mechanism (e.g., Penicillin)
Immune Complex ("Innocent Bystander") Mechanism (e.g., Quinidine)
Membrane Modification (Non-immunologic Protein Adsorption) (e.g., Cephalosporins)
Autoantibody Induction (e.g., Methyldopa)
A patient has a positive DAT. An acid elution is performed, and the eluate reacts with all panel cells. The patient has not been transfused recently. This result is most indicative of:
An alloantibody to a high-frequency antigen.
A warm autoantibody.
Multiple alloantibodies.
A positive DAT due to complement only.
Why is the DAT often negative or only weakly positive in cases of ABO Hemolytic Disease of the Fetus and Newborn (HDFN), despite clinical jaundice?
Fetal red cells possess too many antigen sites, causing prozone.
ABO antibodies are IgM and cannot cross the placenta.
Fetal RBC ABO antigens are poorly developed and have a linear structure rather than branched.
The distance between ABO antigen sites on fetal cells is too wide to be bridged by IgG.
A patient with a positive DAT due to Methyldopa (Aldomet) therapy presents with a pattern identical to WAIHA. The antibody formed is usually:
IgM reacting with all panel cells.
IgG autoantibody.
IgA autoantibody.
IgE autoantibody.
Which of the following conditions is a valid indication for performing a "Differential Allogeneic Adsorption" (using RR1R1, R2R2, and rr cells)?
A. A patient with a cold autoantibody and no history of transfusion.
B. A patient with a warm autoantibody who has been transfused within the last 3 months.
C. A patient with a warm autoantibody who has not been transfused.
D. A patient with an antibody to a high-prevalence antigen.
When performing a DAT using Gel Technology, why is a washing step usually not required for the patient's red cells (unlike the tube method)?
The gel contains enzymes that degrade unbound IgG.
The AHG is incorporated into the gel, and unbound globulins are trapped in the reaction chamber fluid, while cells spin through.
The specific gravity of the gel prevents unbound IgG from migrating.
Gel technology uses IgM antibodies which do not require washing.
A positive DAT may technically invalidate which routine blood bank test if proper controls are not used?
ABO Reverse grouping.
Rh typing with high-protein reagents.
Antibody Screen at Immediate Spin.
Crossmatch at Immediate Spin.
A patient’s serum reacts 2+ with 2 out of 3 screening cells at the AHG phase. On the 11-cell panel, 4 cells are positive. The autocontrol is Negative. The reaction strength is variable (1+ to 3+). What is the most likely explanation?
A. A warm autoantibody.
B. An IgM cold autoantibody.
C. Multiple alloantibodies or an antibody showing Dosage.
D. An antibody to a low-frequency antigen.
The "Rule of Three" in antibody identification is used to establish:
95% confidence (p=0.05) that the antibody identified is the correct one and not a random event.
That the patient has three different antibodies.
That the antibody reacts at three different phases.
That the antibody is IgG.
Polyethylene Glycol (PEG) enhancement is used in the IAT to exclude water molecules and bring cells closer. However, PEG cannot be used if:
The patient has high serum proteins (risk of non-specific precipitation).
The patient is IgA deficient.
The intent is to detect complement-dependent antibodies.
Both A and C.
A patient has a pan-agglutinin (reacts with all panel cells). To distinguish between a Warm Autoantibody and an Alloantibody to a High-Prevalence Antigen, the tech performs an Autoadsorption. The adsorbed serum still reacts with all panel cells. What is the conclusion?
It is a Warm Autoantibody.
It is an Alloantibody to a High-Prevalence antigen.
The adsorption was not performed correctly.
The patient has a Cold Autoantibody.
Which antibody is notoriously difficult to detect because its titer drops rapidly in vivo, causing delayed hemolytic transfusion reactions, and it often shows dosage in vitro?
Anti-K
Anti-Jk(a)
Anti-D
Anti-Le(a)
Use of the enzyme Ficin will destroy reactivity of which second set of antigens?
Rh, Kidd, Lewis, P1
M, N, S, Duffy (Fya/Fyb)
Kell, Dombrock
Lutheran, Kell
A patient with Anti-D and Anti-C is being screened. Which cell would be the most valuable "Selected Cell" to rule out (exclude) the presence of a hidden Anti-Jk(a)?
Cell phenotype: D+, C+, Jk(a+)
Cell phenotype: D-, C-, Jk(a+)
Cell phenotype: D-, C-, Jk(a-)
Cell phenotype: D+, C-, Jk(a+)
High-Titer, Low-Avidity (HTLA) antibodies (e.g., Anti-Chido/Rodgers) are generally considered
clinically insignificant but cause confusion in the lab.
highly pathogenic and require immediate treatment.
responsible for severe transfusion reactions.
useful markers for autoimmune diseases.
Which reagent is used to neutralize Anti-P1, allowing for the detection of underlying alloantibodies?
Saliva
Hydatid Cyst Fluid
Urine from a guinea pig
Breast milk
A patient types as Le(a-b+). Their serum contains an antibody that reacts with Le(a+b-) cells. This antibody is:
Anti-Le(a), which is clinically significant.
Anti-Le(a), which is naturally occurring but generally insignificant in this phenotype (made by Le(a-b+) individuals).
Impossible; Le(a-b+) individuals do not make Lewis antibodies.
Likely Anti-Le(bH).
If a patient has a strong Cold Autoantibody (Anti-I), how can you determine the patient's actual ABO/Rh type without interference?
Perform the test at 4°C.
Wash the red cells with warm (37°C) saline before typing.
Use LISS enhancement.
Use Polyspecific AHG.
Antibodies to which system are often implicated when a patient has a "Negative Screen" but an "Incompatible Crossmatch" (due to a low-frequency antigen on the donor unit)?
Duffy (Fy)
Wright (Wra)
Kell (Kpa)
Kidd (Jk)
P system
The "Major Crossmatch" consists of mixing:
Donor Serum + Patient Red Cells
Patient Serum + Donor Red Cells
Patient Serum + Patient Red Cells
Donor Serum + Donor Red Cells
According to AABB Standards, a "Computer" or "Electronic" Crossmatch may be performed ONLY if:
The antibody screen is currently negative and there is no history of clinically significant antibodies.
The patient has a history of antibodies, but they are currently undetectable.
The computer system has not been validated for ABO logic.
Only one determination of the patient's ABO group is on file.
A patient has a Negative Antibody Screen. The Crossmatch is compatible at Immediate Spin but 2+ Incompatible at AHG. The donor DAT is negative. What is the most likely cause?
ABO incompatibility.
Cold Alloantibody (e.g., Anti-M).
Antibody to a Low-Frequency Antigen (present on donor, not on screen cells).
Donor unit has a positive DAT.
A patient is group A, Rh Negative. You have no A, Rh Neg blood. What is the preferred order of selection for RBC transfusion?
O Neg, then A Pos, then O Pos
O Neg, then O Pos, then A Pos
A Pos, then O Neg, then O Pos
O Pos, then A Pos, then O Neg
Massive Transfusion is defined as replacing a patient's total blood volume within 24 hours (or 10 units). In this setting, the crossmatch procedure is often:
Eliminated (Immediate spin only) to save time, provided the screen was negative.
Performed with full AHG on all units.
Performed using the patient's pre-transfusion sample for the first 24 hours.
Switched to antigen typing only.
You observe a "Mixed Field" reaction in the AHG phase of a crossmatch. The patient has no history of transfusion. The antibody screen is negative. What is a probable cause?
Anti-Sda (Sid)
Anti-K
Anti-D
Weak Anti-A
A patient has Anti-E and Anti-c (Anti-little c). Which donor phenotype is compatible?
R1R1 (DCe/DCe)
R1R2 (DCe/DCe)
rr (dCe/dce)
R2R2 (DcE/DcE)
In an "Immediate Spin" crossmatch, what is the primary incompatibility being detected?
Rh incompatibility.
ABO incompatibility.
Kell incompatibility.
Duffy incompatibility.
A patient has a cold autoantibody (Anti-I). To perform a valid crossmatch, you should:
Use the Pre-warm technique (warm serum and cells to 37°C before mixing).
Perform the crossmatch at 4°C.
Use enzyme-treated donor cells.
Ignore the incompatibility.
When issuing uncrossmatched blood in a trauma emergency, the physician must sign a release. If the patient's type is unknown, you issue Group O Rh-negative. If the patient is a male >18 years old or a female >50 years old, many trauma centers allow the release of:
Group O Rh-positive RBCs (to conserve O Neg).
Group A Rh-positive RBCs.
Group AB Plasma.
Whole Blood.
The "Minor Crossmatch" (Donor Serum + Patient Cells) is deemed obsolete in modern practice because:
Donor antibodies are not significant.
The Antibody Screen on the donor performed by the collection center is sufficient.
Patients always have antibodies.
It consumes too much reagent.
Rouleaux formation can cause false positive crossmatches at the IS phase. This can be distinguished from true agglutination by:
Adding AHG reagent.
Saline Replacement technique.
Heating to 56°C.
Adding albumin.
A patient with Sickle Cell Disease has developed antibodies to C, E, and K. The lab should provide units that are phenotypically matched for these antigens AND:
Are Hemoglobin S negative.
Are from Caucasian donors.
Are irradiated.
Are washed.
In the IAT, "Coombs Control Cells" (Check Cells) are added to all negative tubes. These cells are coated with:
IgM antibodies.
IgG antibodies.
Complement only.
Albumin.
If Coombs Check Cells do NOT agglutinate after being added to a negative IAT, the test is INVALID. The most common technical reason for this failure is:
The patient has no antibody.
Inadequate washing of the red cells (AHG was neutralized by residual serum protein).
The centrifuge speed was too high.
The incubation was too long.
Which of the following describes the "Solid Phase Red Cell Adherence" (SPRCA) assay for antibody screening?
RBCs are embedded in the bottom of a microplate well; patient serum is added; positive reaction = layer of cells across the bottom.
RBCs filter through a dextran-acrylamide gel.
RBCs form a button at the bottom of the well if positive.
It relies on fluorescence.
Low Ionic Strength Saline (LISS) shortens the incubation time of the IAT to 10-15 minutes by:
Increasing the zeta potential.
Decreasing the zeta potential and shielding effect, increasing antibody uptake rate.
Crosslinking IgG molecules.
Activating the classical complement pathway.
Chloroquine diphosphate (CDP) is used in the blood bank to:
Enhance antibody binding.
Dissociate IgG from the RBC surface (clean the cells) without destroying antigens, allowing for phenotyping of DAT+ cells.
Destroy Kell antigens.
Act as a preservative.
ZZAP reagent (a mixture of DTT and Papain) is used to:
A 'False Negative' IAT can be caused by:
Over-centrifugation.
Dirty glassware.
pH of saline below 6.0 (acidic saline dissociates antibody).
Presence of fibrin.
The primary advantage of Gel Technology over Tube testing for Antibody Screening is:
It detects ABO antibodies better.
Standardization of reading (no shaking required) and stability of reactions for review.
It is faster than LISS tube testing.
It uses more sample volume.
An antibody screen is performed using the Tube method. The IS and 37°C phases test negative. The AHG phase is 2+ with all cells. Check cells are okay. The most likely cause is:
An IgM cold agglutinin.
A Warm Autoantibody or Alloantibody to a high-frequency antigen.
Rouleaux.
Dirty glassware.
When looking for a compatible unit for a patient with Anti-N (reacting at AHG), you test 10 units. How many do you expect to be compatible? (N negative frequency is ~30%)
1
3
7
10
Which reagent is required to detect the presence of Anti-C3d on red cells?
Monospecific Anti-IgG
Monospecific Anti-C3d/C3b
Polyspecific AHG
Bovine Albumin
Which of the following antigens is known to deteriorate rapidly on stored red blood cells, potentially causing a false-negative control result if old reagent cells are used?
D antigen
K antigen
P1 antigen
e antigen
A patient has an antibody identified as Anti-D. However, the reaction strength varies significantly between different D-positive cells on the panel. This is most likely due to:
The 'Dosage' effect (Rh antigens do not typically show dosage, but this is a distractor).
Variation in the amount of D antigen on D+ target cells (e.g., R2R2 cells have more D than R1r cells).
Contamination.
Presence of Anti-I.
To confirm the presence of Anti-Leb in a pregnant patient who types as Le(a-b-), you can:
Use enzyme-treated cells (Lewis antibodies are enhanced).
Perform a neutralization test with Lewis Substance.
Both A and B.
Neither; Lewis antibodies are not found in pregnancy.
In the 'Donath-Landsteiner' test for Paroxysmal Cold Hemoglobinuria (PCH), the patient's serum is incubated with P-positive cells at 4°C and then warmed to 37°C. A positive result is indicated by:
Agglutination at 4°C.
Agglutination at 37°C.
Hemolysis after warming to 37°C.
Precipitation.
Refusal to perform a crossmatch (holding blood) is appropriate when:
The patient has a positive antibody screen but the antibody is not yet identified.
The patient has a history of antibodies but the screen is now negative.
The physician ordered it 'STAT'.
The sample is 24 hours old.
Neonatal crossmatching (for an infant < 4 months old) generally requires:
Testing infant serum against donor RBCs.
Testing maternal serum against donor RBCs (preferred, as infant has no antibodies of their own).
Testing infant RBCs against donor serum.
Full AHG crossmatch.
Cephalosporins (like Keflin) can modify the ______ membrane so that plasma proteins absorb non-specifically.
RBC
muscle
nerve
bone
A positive DAT with an acid eluate reacting with all cells is the classic definition of a ______ autoantibody.
warm
cold
mixed
neutral
Fetal ABO antigens are ______ and less developed.
linear
branched
circular
complex
Methylodopa induces an autoantibody that mimics ______ specificity.
Rh
ABO
Kell
Duffy
If the patient has been transfused recently, you must use ______ cells to adsorb the autoantibody and leave the alloantibody behind.
allogeneic
autologous
leukocyte
platelet
In Gel, the anti-IgG is in the ______ matrix.
gel
agarose
polyacrylamide
cellulose
High-protein anti-D contains potentiators that can cause spontaneous agglutination of ______-coated cells.
IgG
IgM
C3d
Albumin
Variable reaction strengths usually indicate ______ or the presence of multiple antibodies.
Dosage
Agglutination
Hemolysis
Incubation
3 positives and 3 negatives result in a p-value of ______.
0.05
0.01
0.10
0.20
PEG precipitates ______ and inhibits complement detection.
proteins
lipids
carbohydrates
nucleic acids
If the serum still reacts with panel cells after autoadsorption, the antigen is ______ on the patient's cells.
not
present
weak
masked
Jk(a) antibodies are the leading cause of delayed ______ transfusion reactions.
hemolytic
febrile
allergic
anaphylactic
Enzymes cleave ______ acid-rich antigens.
sialic
lactic
citric
acetic
To rule out Jk(a), you need a cell that is ______ for Jk(a) but Negative for the antibodies you already know exist.
Positive
Negative
Reactive
Inconclusive
HTLA antibodies react ______ but maintain that weak strength even when diluted significantly.
weakly
strongly
quickly
slowly
Hydatid cyst fluid contains ______ substance.
P1
Albuminous
Serous
Mucous
A person who is Le(a-b+) has the ______ gene and Se gene.
Le
Rh
Kell
Duffy
Washing with ______°C saline removes the cold autoantibody and allows for valid typing.
37
25
45
10
Low-frequency antigens are not usually on ______ cells.
screening
red blood
white blood
plasma
Tests for patient antibodies against ______ cells.
donor
red blood
white blood
platelet
Electronic crossmatch requires a validated system, two ______ determinations, and no current or history of antibodies.
ABO
Rh
HLA
Kell
C (Low-Freq Antigen). Similar to Q20. Fill in the blank: The screen is _______ , AHG Crossmatch _______ .
negative, positive
positive, negative
positive, positive
negative, negative
Fill in the blank: O Neg is _______. A Pos is type specific but _______ incompatible. O Pos is compatible red cells but _______ incompatible.
compatible, Rh, Rh
incompatible, ABO, ABO
universal, ABO, Rh
compatible, ABO, ABO
Once blood volume is replaced, the patient's original antibodies are _______. We usually switch to _______ crossmatch or just ABO compatible release.
diluted, IS
increased, AHG
unchanged, saline
destroyed, gel
Sid causes ________, mixed-field agglutination.
shiny
dull
sticky
cloudy
A (RR11). RR11 is DCe/DCe. It lacks E and lacks c. (R1R2 has E and c; rr has c; R2R2 has E and c). Fill in the blank: RR11 is _______/______. It lacks _______ and lacks _______.
DCe/DCe, E, c
R1R2, c, E
rr, E, DCe
R2R2, DCe, c
IS detects _______ antibodies, primarily _______.
IgM, ABO
IgG, Rh
IgA, Kell
IgE, Duffy
Pre-warm prevents the _______ antibody from binding, allowing detection of clinically significant _______ antibodies.
cold, IgG
warm, IgM
IgG, cold
IgM, warm
O Pos is used for _______ and women > _______ age to save O Neg for women of childbearing age.
males, childbearing
females, 40
males, 60
children, 18
We test donor units for _______ at the blood center. If negative, minor crossmatch is _______.
antibodies, redundant
antigens, necessary
enzymes, required
proteins, essential
Fill in the blank: Remove serum, replace with _______. If it disperses = _______. If it stays = _______.
saline, Rouleaux, Agglutination
water, Agglutination, Rouleaux
plasma, Agglutination, Rouleaux
buffer, Rouleaux, Agglutination
Sickle cell patients should receive _______ negative blood to ensure effective oxygen carrying capacity and prevent sickling of donor cells.
HbS
HbA
HbF
HbC
Check cells are _______ sensitized. They verify the _______ reagent is active.
IgG, AHG
IgM, saline
IgA, enzyme
IgE, albumin
Residual serum _______ the AHG.
neutralizes
activates
destroys
enhances
Fill in the blank: In Solid Phase, antigen is on the _______. Antibody binds. Indicator cells bind to antibody, forming a _______ (Positive). If no antibody, indicator cells pellet to the bottom (_______ button).
well, carpet, Negative
slide, mat, Positive
tube, layer, Neutral
plate, sheet, Negative
LISS lowers _______ strength, reducing the ion cloud, allowing antibody to bind _______.
ionic, faster
covalent, slower
hydrogen, weaker
electrostatic, less
Used to treat _______ cells so they can be phenotyped.
DAT+
RBC
WBC
T-cell
ZZAP cleans cells for _______ but destroys _______/______.
autoadsorption, Duffy, MNS
alloantibody, Kell, Lewis
enzyme treatment, Rh, Kidd
adsorption, Lutheran, P
Low pH can cause antibody _______/______.
elution/dissociation
aggregation/precipitation
activation/degradation
synthesis/replication
Fill in the blank: Standardization.
Standardization
Optimization
Diversification
Customization
Reactions at AHG only with all cells usually imply an _______ antibody against a common antigen or an _______.
IgG, autoantibody
IgM, alloantibody
IgA, heterophile antibody
IgE, drug-dependent antibody
Fill in the blank: 30% are negative. 10×0.30=______.
3
0.3
30
0
Fill in the blank: Monospecific Anti-C3.
Monospecific Anti-C3
Monospecific Anti-IgG
Monospecific Anti-A
Monospecific Anti-B
Fill in the blank: P1 is _______ and weakens in storage.
labile
stable
volatile
inert
The D antigen has _______ and density differences (R2 cells have more D sites than R1).
mosaicism
polymorphism
isomerism
homogeneity
Fill in the blank: Lewis is enhanced by _______ and can be _______.
enzymes, neutralized
acids, oxidized
bases, reduced
solvents, dissolved
Fill in the blank: The DL antibody binds in _______ (fix complement) and _______ when warm.
cold, lyses
warm, agglutinates
cold, agglutinates
warm, lyses
You cannot crossmatch until the antibody is _______ and antigen-negative blood is _______.
identified, found
found, identified
tested, matched
removed, replaced
Fill in the blank: The infant has not formed antibodies yet; _______ serum has the IgG antibodies that matter.
maternal
paternal
infant
donor
Which blood group system antigens are located on the Anion Exchanger 1 (AE1), also known as Band 3, and are essential for the structural integrity of the red cell membrane?
Colton (Co)
Diego (Di)
Cromer (Cr)
Dombrock (Do)
