MLT GlobeBlood Banking: Blood components & storage – page 4
109 Blood Banking MCQs on Blood components & storage with answers and explanations.
The standard gamma irradiation dose for blood components is:
AABB requires a minimum of 25 Gy to the central point and at least 15 Gy to any other part of the component, which inactivates lymphocytes.
A red cell unit with 30 days left is irradiated today. Its new expiration is:
Irradiated red cells expire 28 days after irradiation or at the original expiry, whichever comes first. Irradiation increases potassium leak.
A patient will receive red cells donated by his brother. The unit must be:
Blood from blood relatives may share HLA haplotypes, so donor lymphocytes may not be rejected and can cause TA-GVHD. Irradiation prevents this.
Plasma cryoprecipitate reduced (cryo-poor plasma) is sometimes used for plasma exchange in TTP because it:
Removing cryoprecipitate removes most fibrinogen, factor VIII and large VWF multimers, while ADAMTS13 remains. This makes it an alternative replacement fluid in TTP.
The usual adult dose of plasma for correcting multiple factor deficiencies is:
A dose of 10–20 mL/kg raises most factor levels by about 20–30%. Smaller doses rarely correct coagulopathy.
In the platelet-rich plasma method, the first centrifugation of whole blood is a:
A light spin leaves platelets in the plasma (PRP). A second heavy spin then concentrates the platelets, and most plasma is removed.
Whole blood intended for platelet preparation should be kept before processing at:
Cooling activates platelets and shortens their survival, so whole blood for platelet production is held at room temperature until separation.
Whole-blood-derived platelets pooled in an open system expire after:
Pooling in an open system raises contamination risk, so the pool expires 4 hours after pooling. Prestorage closed-system pools keep the original expiry.
Granulocyte concentrates should be:
Granulocytes lose function quickly, so they are kept at room temperature without agitation and given as soon as possible, within 24 hours. They must also be irradiated.
A rejuvenation solution containing pyruvate, inosine, phosphate and adenine is used to:
Rejuvenation restores 2,3-DPG and ATP in red cells near expiry; the cells are then washed and may be frozen or transfused within 24 hours.
On inspection, a red cell bag is dark purple while its attached segments are normal red. The most likely cause is:
A color difference between the bag and its segments suggests bacterial growth (e.g., Yersinia) with hemolysis and low oxygen. The unit must be quarantined and not issued.
A D-negative woman aged 28 must receive D-positive apheresis platelets. To prevent anti-D formation, she should receive:
Platelet units contain small amounts of D-positive red cells that can immunize. Rh immune globulin (a standard 300 µg dose covers many units) prevents anti-D.
A hospital wants to extend the dating of its apheresis platelets from 5 to 7 days. Which measure allows this under current FDA guidance?
Large-volume, delayed sampling culture reduces the risk of bacterial contamination enough to permit 7-day storage. Irradiation and leukoreduction prevent TA-GVHD and leukocyte effects but do not address bacteria.
Cold-stored platelets (1–6 °C, no agitation) are used in some centres. They are mainly intended for:
Cold-stored platelets are cleared from the circulation faster but are more hemostatically active, so they suit actively bleeding patients. They are not suited to prophylaxis, where long survival is needed.
Why are conventional platelet units NOT stored in the refrigerator?
Chilling changes platelet GPIb, and these platelets are quickly removed by liver macrophages, so their survival is short. Bacteria actually grow better at room temperature, not in the cold.
Replacing most of the plasma in an apheresis platelet unit with platelet additive solution (PAS) mainly reduces:
PAS lowers the plasma volume, so there are fewer plasma proteins causing allergic reactions and less isoagglutinin in ABO-mismatched transfusions. It does not affect lymphocytes (TA-GVHD) or HLA antigens.
A technologist holds a platelet unit to the light and gently presses it. A shimmering, cloudy swirling pattern is seen. This finding indicates:
The 'swirling' effect is due to light scattering by discoid platelets and is a sign of good viability. Loss of swirling suggests platelets have become spherical, often from a fall in pH.
Under FDA criteria, hemolysis in a red cell unit at the end of its storage period must be less than:
FDA requires end-of-storage hemolysis below 1% (European standards use 0.8%). Higher hemolysis indicates poor red cell quality or damage during processing.
An adult has a plasma volume of 3000 mL and fibrinogen of 80 mg/dL. The target is 180 mg/dL. If each cryoprecipitate unit contains 250 mg fibrinogen, how many units are needed?
Required fibrinogen = 100 mg/dL × 30 dL = 3000 mg. 3000 mg ÷ 250 mg per unit = 12 units. Forgetting to convert mL to dL gives a wrong answer.
A single unit of cryoprecipitate is thawed and NOT pooled. It is kept at 20–24 °C. It must be transfused within:
Thawed single (or closed-system pooled) cryoprecipitate expires 6 hours after thawing at room temperature. The 4-hour limit applies when pooling is done in an open system.