A leukocyte-reduced red cell unit of 300 mL has 12 residual white cells per µL. The unit contains:

3.6 × 10^6 white cells and meets the US standard

3.6 × 10^6 white cells and fails the US standard

3.6 × 10^9 white cells and fails the US standard

3.6 × 10^3 white cells and meets the US standard

Each cryoprecipitate unit must contain at least:

80 IU of factor VIII and 150 mg of fibrinogen

50 IU of factor VIII and 100 mg of fibrinogen

150 IU of factor VIII and 80 mg of fibrinogen

250 IU of factor VIII and 500 mg of fibrinogen

Blood component quality control

7 ASCP MLS practice questions on Blood component quality control, part of Blood Banking. The first 7 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 · Hard
A leukocyte-reduced red cell unit of 300 mL has 12 residual white cells per µL. The unit contains:
1. A3.6 × 10^6 white cells and fails the US standard
2. B3.6 × 10^9 white cells and fails the US standard
3. C3.6 × 10^3 white cells and meets the US standard
4. D3.6 × 10^6 white cells and meets the US standard
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Answer: D · 3.6 × 10^6 white cells and meets the US standard
300 mL is 300,000 µL, so the unit holds 12 × 300,000 = 3.6 × 10^6 white cells. This is below the US limit of 5 × 10^6, so it meets the standard. Residual white cells are too few for routine analyzers and are counted with a large-volume (Nageotte) chamber or flow cytometry. The unit must also keep at least 85% of its original red cells.
- A: 3.6 × 10^6 is below the 5 × 10^6 limit, so it passes.
- B: 3.6 × 10^9 comes from using 10^6 µL per mL instead of 10^3.
- C: 3.6 × 10^3 comes from treating the count as per mL instead of per µL.
Question 2 · Easy
In quality control, at least 90% of whole blood-derived platelet units tested must contain at least:
1. A8.3 × 10^5 platelets
2. B1.0 × 10^10 platelets
3. C5.5 × 10^10 platelets
4. D3.0 × 10^11 platelets
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Answer: C · 5.5 × 10^10 platelets
AABB requires at least 5.5 × 10^10 platelets in 90% of whole blood-derived platelet units tested. For apheresis platelets the limit is 3.0 × 10^11. Units must also keep a pH of at least 6.2 at the end of storage. QC results are tracked over time to spot problems in collection or processing.
- A: 8.3 × 10^5 is the white cell limit for leukocyte-reduced whole blood-derived platelets.
- B: 1.0 × 10^10 is far below the required platelet content.
- D: 3.0 × 10^11 is the limit for apheresis platelets.
Question 3 · Hard
Deglycerolized red cells must keep at least 80% of the original red cells. A unit had 180 mL of red cells before freezing and 135 mL after deglycerolization. The result is:
1. A75%; the unit passes QC
2. B133%; the unit passes QC
3. C75%; the unit fails QC
4. D25%; the unit fails QC
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Answer: C · 75%; the unit fails QC
Recovery = red cells after ÷ red cells before = 135 ÷ 180 = 0.75, or 75%. This is below the required 80%, so the unit fails the recovery standard. Low recovery points to hemolysis during freezing, thawing or washing. The washing process is also checked for adequate glycerol removal.
- A: 75% is below the 80% requirement, so the unit does not pass.
- B: 133% comes from dividing the wrong way round.
- D: 25% is the loss, not the recovery.
Question 4 · Medium
At the end of storage, platelet units must have a pH of at least:
1. A5.5
2. B6.2
3. C6.8
4. D7.4
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Answer: B · 6.2
AABB requires platelet units to keep a pH of at least 6.2 at the end of storage. Below this, platelets lose their disc shape irreversibly and survive poorly after transfusion. pH falls when lactic acid builds up during poor oxygen supply. Gas-permeable bags and continuous agitation help keep pH acceptable.
- A: 5.5 is far below the required minimum.
- C: 6.8 is higher than the required minimum.
- D: 7.4 is the normal blood pH, not the storage limit.
Question 5 · Medium
Each cryoprecipitate unit must contain at least:
1. A50 IU of factor VIII and 100 mg of fibrinogen
2. B150 IU of factor VIII and 80 mg of fibrinogen
3. C250 IU of factor VIII and 500 mg of fibrinogen
4. D80 IU of factor VIII and 150 mg of fibrinogen
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Answer: D · 80 IU of factor VIII and 150 mg of fibrinogen
AABB requires at least 80 IU of factor VIII and 150 mg of fibrinogen per cryoprecipitate unit. Pooled cryoprecipitate must meet these amounts multiplied by the number of units. In practice units often average about 250 mg of fibrinogen, which is why dosing formulas use 250 mg. Cryoprecipitate also contains von Willebrand factor, factor XIII and fibronectin.
- A: These values are below the required minimums.
- B: This swaps the two minimum values.
- C: These values are higher than the required minimums.
Question 6 · Hard
Monthly quality control is performed on four leukocyte-reduced apheresis platelet units. The limits are at least 3.0 × 10^11 platelets and fewer than 5.0 × 10^6 white cells per unit. Results (platelets in × 10^3/µL; residual white cells per µL by flow cytometry): unit 1, volume 230 mL, platelets 1,320, white cells 12; unit 2, volume 300 mL, platelets 1,050, white cells 16; unit 3, volume 260 mL, platelets 1,300, white cells 21; unit 4, volume 200 mL, platelets 1,600, white cells 24. The unit that fails quality control is:
1. AUnit 2, for its platelet content
2. BUnit 3, for its white cell content
3. CUnit 1, for its platelet content
4. DUnit 4, for its white cell content
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Question 7 · Medium
The table shows quality control results for four single units of cryoprecipitated AHF. Which units fail the AABB requirements?
Figure: MedExams
1. AUnits 3 and 4
2. BUnit 3 only
3. CUnits 2 and 4
4. DUnit 4 only
Answer and explanation in LearnFree account

Blood component quality control

A leukocyte-reduced red cell unit of 300 mL has 12 residual white cells per µL. The unit contains:

In quality control, at least 90% of whole blood-derived platelet units tested must contain at least:

Deglycerolized red cells must keep at least 80% of the original red cells. A unit had 180 mL of red cells before freezing and 135 mL after deglycerolization. The result is:

At the end of storage, platelet units must have a pH of at least:

Each cryoprecipitate unit must contain at least:

The table shows quality control results for four single units of cryoprecipitated AHF. Which units fail the AABB requirements?