Which finding most strongly confirms that a platelet unit caused a septic transfusion reaction?

The same organism grows from the unit and the patient's blood

The unit's culture grows skin flora but the patient's is negative

The patient's white cell count rises after the transfusion

The patient's temperature rises by more than 2 °C

A febrile nonhemolytic reaction is a diagnosis of exclusion. Before it is made, the workup must rule out:

Acute hemolysis and bacterial contamination

Post-transfusion purpura and TA-GVHD

Circulatory overload and allergic reaction

Iron overload and red cell alloimmunization

In a reaction workup, the clerical check shows that the unit given to Patient 1 had been crossmatched for Patient 2 on the same ward. Besides caring for Patient 1, what is the most urgent action?

Check at once whether Patient 2 received a wrong unit too

Repeat the crossmatch of the unit with Patient 1's sample

Wait for the DAT result before reporting the error

Retype the donor unit from an attached segment first

A group O, D-positive patient is given a group A red cell unit by mistake. Which set of findings in the post-transfusion sample is expected?

Mixed-field reaction with anti-A, positive DAT, hemolyzed plasma

Group O, negative DAT, clear plasma, no new antibody

Group O, IgG-only DAT, clear plasma, new anti-Jka

Group A on all cells, negative DAT, clear plasma

A 56-year-old man receives 2 red cell units after surgery; his pretransfusion antibody screen was negative. His hemoglobin rises from 76 to 95 g/L (7.6 to 9.5 g/dL). On day 8, without bleeding, it is 73 g/L (7.3 g/dL), bilirubin is 58 µmol/L (3.4 mg/dL; reference below 21 µmol/L), the DAT is positive with IgG and a new anti-Jkb is found in plasma and eluate. The most likely diagnosis is:

Delayed hemolytic reaction from anamnestic anti-Jkb

Acute hemolytic reaction from a clerical error

Delayed serologic reaction without hemolysis

Warm autoimmune hemolytic anemia

Transfusion reactions and investigation

23 DOH Abu Dhabi (HAAD) lab licensing practice questions on Transfusion reactions and investigation, part of Blood Banking. The first 23 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 · Medium
Which finding most strongly confirms that a platelet unit caused a septic transfusion reaction?
1. AThe same organism grows from the unit and the patient's blood
2. BThe unit's culture grows skin flora but the patient's is negative
3. CThe patient's white cell count rises after the transfusion
4. DThe patient's temperature rises by more than 2 °C
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Answer: A · The same organism grows from the unit and the patient's blood
A septic reaction is confirmed when the same organism, ideally shown to be the same strain by molecular typing, is found in the component and in the recipient's blood. High fever and rigors are suggestive but not specific. A positive bag culture alone may reflect contamination during handling after the reaction, especially with skin organisms. The patient's blood cultures should be drawn before antibiotics are started.
- B: Skin flora in the bag alone may be contamination after the event, and the patient's culture does not support it.
- C: A raised white count is nonspecific and does not link the infection to the unit.
- D: A large temperature rise suggests sepsis but also occurs in hemolytic and febrile reactions.
Question 2 · Medium
A febrile nonhemolytic reaction is a diagnosis of exclusion. Before it is made, the workup must rule out:
1. APost-transfusion purpura and TA-GVHD
2. BAcute hemolysis and bacterial contamination
3. CCirculatory overload and allergic reaction
4. DIron overload and red cell alloimmunization
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Answer: B · Acute hemolysis and bacterial contamination
Fever, with or without chills, is the main sign of a febrile nonhemolytic reaction, but it is also an early sign of acute hemolysis and of a septic reaction, both of which can be fatal. The workup therefore includes a clerical check, visual inspection of the plasma for hemolysis and a DAT, plus Gram stain and culture of the unit when sepsis is suspected (high fever, rigors, hypotension). Only when these are negative is the reaction called febrile nonhemolytic. Prestorage leukoreduction lowers the risk of these reactions.
- A: PTP and TA-GVHD appear days later, not as fever during the transfusion.
- C: Circulatory overload causes dyspnea and hypertension, and allergy causes hives; neither is a usual cause of fever alone.
- D: Iron overload and alloimmunization are delayed effects, not causes of fever during transfusion.
Question 3 · Hard
In a reaction workup, the clerical check shows that the unit given to Patient 1 had been crossmatched for Patient 2 on the same ward. Besides caring for Patient 1, what is the most urgent action?
1. ARepeat the crossmatch of the unit with Patient 1's sample
2. BWait for the DAT result before reporting the error
3. CRetype the donor unit from an attached segment first
4. DCheck at once whether Patient 2 received a wrong unit too
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Answer: D · Check at once whether Patient 2 received a wrong unit too
When one unit reaches the wrong patient, the unit meant for that patient has often been given to the other, so a second incompatible transfusion may be under way. The blood bank and ward must at once trace every unit issued for both patients and stop any wrong transfusion. Repeat ABO/Rh typing, a DAT and a visual check for hemolysis on both patients' samples follow. The error is reported through hemovigilance and investigated as a serious event.
- A: Recrossmatching does not address the risk to the other patient and delays the urgent step.
- B: A negative DAT would not make the error less serious, and waiting delays protection of the other patient.
- C: Retyping the unit is part of the workup, but it is not the most urgent step for patient safety.
Question 4 · Hard
A group O, D-positive patient is given a group A red cell unit by mistake. Which set of findings in the post-transfusion sample is expected?
1. AGroup O, negative DAT, clear plasma, no new antibody
2. BGroup O, IgG-only DAT, clear plasma, new anti-Jka
3. CGroup A on all cells, negative DAT, clear plasma
4. DMixed-field reaction with anti-A, positive DAT, hemolyzed plasma
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Answer: D · Mixed-field reaction with anti-A, positive DAT, hemolyzed plasma
The surviving group A donor cells react with anti-A while the patient's own O cells do not, giving a mixed-field forward grouping. The patient's IgM anti-A binds the donor cells and fixes complement, so the DAT is usually positive (often with anti-C3), and free hemoglobin makes the plasma pink or red. An eluate from the cells contains anti-A. Group A on all cells would suggest instead that the sample came from another patient.
- A: Normal results like these do not fit an incompatible transfusion with surviving donor cells.
- B: A new anti-Jka with an IgG DAT and clear plasma fits a delayed serologic reaction, not ABO incompatibility.
- C: Group A on all cells means the sample probably came from another patient (wrong blood in tube).
Question 5 · Hard
A 56-year-old man receives 2 red cell units after surgery; his pretransfusion antibody screen was negative. His hemoglobin rises from 76 to 95 g/L (7.6 to 9.5 g/dL). On day 8, without bleeding, it is 73 g/L (7.3 g/dL), bilirubin is 58 µmol/L (3.4 mg/dL; reference below 21 µmol/L), the DAT is positive with IgG and a new anti-Jkb is found in plasma and eluate. The most likely diagnosis is:
1. AAcute hemolytic reaction from a clerical error
2. BDelayed serologic reaction without hemolysis
3. CDelayed hemolytic reaction from anamnestic anti-Jkb
4. DWarm autoimmune hemolytic anemia
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Answer: C · Delayed hemolytic reaction from anamnestic anti-Jkb
The patient had made anti-Jkb earlier, from a transfusion or pregnancy, but it had fallen below detectable levels, so the screen was negative. The transfused Jk(b+) cells triggered an anamnestic IgG response, and the coated donor cells were removed, so the hemoglobin fell back to its pretransfusion level and the bilirubin rose. Because there is evidence of hemolysis, this is a delayed hemolytic reaction rather than a delayed serologic one. Future red cells must be Jk(b-) and crossmatch-compatible by the antiglobulin method, and the antibody should be recorded permanently.
- A: An acute reaction would appear within 24 hours, not on day 8.
- B: A delayed serologic reaction has a new antibody without a falling hemoglobin or raised bilirubin.
- D: A warm autoantibody would react with all cells; this eluate shows one alloantibody specificity.
Question 6 · Medium
Six hours after a suspected acute hemolytic reaction, which set of results supports hemolysis?
1. AHigh haptoglobin, high LD, normal bilirubin
2. BLow haptoglobin, normal LD, low unconjugated bilirubin
3. CHigh haptoglobin, normal LD, high conjugated bilirubin
4. DLow haptoglobin, high LD, high unconjugated bilirubin
Answer and explanation in LearnFree account
Question 7 · Hard
Two weeks after cardiac surgery with nonirradiated transfusions, a man has fever, a rash, diarrhea and pancytopenia. TA-GVHD is suspected. Which test best confirms it?
1. AA positive direct antiglobulin test with IgG
2. BHLA antibodies found in the donor's plasma
3. CA hypocellular marrow on bone marrow biopsy
4. DDonor lymphocytes or DNA found in his blood or skin
Answer and explanation in LearnFree account
Question 8 · Hard
A red cell unit is infused through a line that is also running 5% dextrose. The patient's urine turns red. The clerical check and repeat ABO/Rh find no error, and the DAT and antibody screen are negative. The most likely cause is:
1. ABacterial contamination of the red cell unit
2. BOsmotic lysis of red cells from the dextrose
3. CA wrong unit given to the patient
4. DAn antibody missed by the antibody screen
Answer and explanation in LearnFree account
Question 9 · Medium
In a confirmed ABO-incompatible transfusion, the post-transfusion plasma is red, yet the DAT is negative. The best explanation is that:
1. AThe EDTA sample tube prevented a positive DAT
2. BIgM anti-A cannot activate complement on red cells
3. CThe DAT detects autoantibodies but not alloantibodies
4. DThe incompatible donor cells were already destroyed
Answer and explanation in LearnFree account
Question 10 · Medium
A 79-year-old woman with heart failure has a hemoglobin of 68 g/L (6.8 g/dL) and is to receive red cells. Which plan best reduces her risk of circulatory overload?
1. ALeukoreduced and irradiated red cells
2. BWashed red cells to remove the plasma
3. CAntihistamine and paracetamol premedication
4. DOne unit at a time, slowly, with review between units
Answer and explanation in LearnFree account
Question 11 · Medium
A few minutes into a plasma transfusion, a patient develops wheezing and hypotension without fever. Which test on the pretransfusion sample is most useful to find the cause?
1. AIgA level and anti-IgA
2. BMast cell tryptase level
3. CRed cell antibody screen
4. DDirect antiglobulin test
Answer and explanation in LearnFree account
Question 12 · Hard
In a TRALI investigation, the implicated plasma came from a woman with three pregnancies. She has anti-HLA-A2, and the patient types HLA-A2 positive. How is this interpreted?
1. AA finding that excludes TRALI and points to TACO
2. BEvidence that the patient's own HLA antibodies caused it
3. CA cognate antibody that supports antibody-mediated TRALI
4. DAn incidental finding unless the patient's DAT is positive
Answer and explanation in LearnFree account
Question 13 · Easy
Post-transfusion purpura is most often caused by an antibody to which platelet antigen?
1. AHPA-3a
2. BHPA-5b
3. CHPA-1a
4. DHLA class I
Answer and explanation in LearnFree account
Question 14 · Easy
Most ABO-incompatible red cell transfusions are caused by:
1. AWeak reactions in the reverse grouping
2. BMisidentifying the patient or the sample
3. CAn antibody missed in the antibody screen
4. DFailure of the anti-A or anti-B reagent
Answer and explanation in LearnFree account
Question 15 · Medium
A delayed hemolytic reaction is found with a new anti-Jka. To learn whether the antibody was present but missed before transfusion, the laboratory should test:
1. AA segment of the donor unit with a DAT
2. BA titer of anti-Jka in the current plasma sample
3. CThe stored pretransfusion sample for antibodies
4. DThe patient's post-transfusion cells for Jka
Answer and explanation in LearnFree account
Question 16 · Hard
A Gram stain of a platelet unit implicated in a septic reaction shows gram-positive cocci in clusters. Besides caring for the patient, which action best protects other recipients?
1. ADiscard every platelet unit currently in the hospital inventory
2. BSwitch all patients to whole blood-derived platelets
3. CAsk the supplier to quarantine co-components of that donation
4. DIrradiate all remaining platelets from that blood supplier
Answer and explanation in LearnFree account
Question 17 · Medium
In the two-hit model of TRALI, the first hit is usually:
1. ADonor HLA or HNA antibodies in the transfused plasma
2. BFluid overload from a rapid infusion rate
3. CThe patient's illness priming neutrophils in the lungs
4. DRecipient IgE against donor plasma proteins
Answer and explanation in LearnFree account
Question 18 · Easy
In hemovigilance reporting (ISBT definitions), imputability describes:
1. AWhether the event could have been prevented
2. BHow severe the adverse reaction was
3. CHow likely the transfusion caused the event
4. DHow soon the symptoms began after transfusion
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Question 19 · Medium
An hour after a suspected transfusion reaction, the urine is red. The dipstick blood test is strongly positive, microscopy shows 0 to 2 red cells per high-power field, and the plasma is pink. This indicates:
1. ABilirubinuria from extravascular hemolysis
2. BHematuria from trauma by the bladder catheter
3. CMyoglobinuria from muscle damage
4. DHemoglobinuria from intravascular hemolysis
Answer and explanation in LearnFree account
Question 20 · Hard
In a reaction workup, the post-transfusion sample, drawn slowly through a narrow catheter, is pink; the pretransfusion plasma was clear. The clerical check finds no error, the DAT is negative, the first urine is clear and haptoglobin is normal. The best next step is:
1. APerform an eluate on the post-transfusion cells
2. BCollect a new sample by clean venipuncture
3. CCulture the unit for bacterial contamination
4. DReport an acute hemolytic transfusion reaction
Answer and explanation in LearnFree account
Question 21 · Easy
A surgical patient is transfused on day 0. If an anamnestic antibody to a donor antigen then causes hemolysis, it usually shows:
1. AWithin the first 24 hours
2. BBetween about day 3 and day 14
3. CWithin the first hour
4. DAfter about 2 to 3 months
Answer and explanation in LearnFree account
Question 22 · Hard
A 66-year-old woman with three previous pregnancies receives 2 red cell units during hip surgery (day 0) and then enoxaparin prophylaxis. Platelets: day 0, 245 × 10^9/L; day 5, 228 × 10^9/L; day 9, 6 × 10^9/L, with widespread purpura and nosebleeds but no thrombosis. PT, APTT and fibrinogen are normal. Anti-PF4/heparin ELISA: optical density 0.18 (positive at 0.40 or more). Platelet antibody testing finds anti-HPA-1a, and her own platelets type HPA-1a negative (HPA-1b/1b). Which diagnosis and first treatment fit best?
1. APost-transfusion purpura; random-donor platelets
2. BDisseminated intravascular coagulation; plasma
3. CPost-transfusion purpura; high-dose IVIG
4. DHeparin-induced thrombocytopenia; argatroban
Answer and explanation in LearnFree account
Question 23 · Hard
A 61-year-old man with myelodysplasia starts a red cell unit collected 35 days earlier (AS-1, 42-day shelf life). After 15 minutes he has rigors, his temperature rises from 37.0 °C to 40.2 °C and his blood pressure falls to 78/40 mm Hg; oozing from his cannula site follows. The clerical check is correct, the post-transfusion plasma is not hemolyzed and the DAT is negative. A Gram stain of the bag contents shows gram-negative coccobacilli. Cultures of the bag and of the patient's blood grow the same lactose-nonfermenting organism: it grows at 4 °C, is oxidase negative and urease positive, and is motile at 25 °C but not at 37 °C. The most likely organism is:
1. APseudomonas fluorescens
2. BSerratia marcescens
3. CStaphylococcus epidermidis
4. DYersinia enterocolitica
Answer and explanation in LearnFree account

Transfusion reactions and investigation

Which finding most strongly confirms that a platelet unit caused a septic transfusion reaction?

A febrile nonhemolytic reaction is a diagnosis of exclusion. Before it is made, the workup must rule out:

In a reaction workup, the clerical check shows that the unit given to Patient 1 had been crossmatched for Patient 2 on the same ward. Besides caring for Patient 1, what is the most urgent action?

A group O, D-positive patient is given a group A red cell unit by mistake. Which set of findings in the post-transfusion sample is expected?

Six hours after a suspected acute hemolytic reaction, which set of results supports hemolysis?

Two weeks after cardiac surgery with nonirradiated transfusions, a man has fever, a rash, diarrhea and pancytopenia. TA-GVHD is suspected. Which test best confirms it?

A red cell unit is infused through a line that is also running 5% dextrose. The patient's urine turns red. The clerical check and repeat ABO/Rh find no error, and the DAT and antibody screen are negative. The most likely cause is:

In a confirmed ABO-incompatible transfusion, the post-transfusion plasma is red, yet the DAT is negative. The best explanation is that:

A 79-year-old woman with heart failure has a hemoglobin of 68 g/L (6.8 g/dL) and is to receive red cells. Which plan best reduces her risk of circulatory overload?

A few minutes into a plasma transfusion, a patient develops wheezing and hypotension without fever. Which test on the pretransfusion sample is most useful to find the cause?

In a TRALI investigation, the implicated plasma came from a woman with three pregnancies. She has anti-HLA-A2, and the patient types HLA-A2 positive. How is this interpreted?

Post-transfusion purpura is most often caused by an antibody to which platelet antigen?

Most ABO-incompatible red cell transfusions are caused by:

A delayed hemolytic reaction is found with a new anti-Jka. To learn whether the antibody was present but missed before transfusion, the laboratory should test:

A Gram stain of a platelet unit implicated in a septic reaction shows gram-positive cocci in clusters. Besides caring for the patient, which action best protects other recipients?

In the two-hit model of TRALI, the first hit is usually:

In hemovigilance reporting (ISBT definitions), imputability describes:

An hour after a suspected transfusion reaction, the urine is red. The dipstick blood test is strongly positive, microscopy shows 0 to 2 red cells per high-power field, and the plasma is pink. This indicates:

In a reaction workup, the post-transfusion sample, drawn slowly through a narrow catheter, is pink; the pretransfusion plasma was clear. The clerical check finds no error, the DAT is negative, the first urine is clear and haptoglobin is normal. The best next step is:

A surgical patient is transfused on day 0. If an anamnestic antibody to a donor antigen then causes hemolysis, it usually shows: