MLT GlobeBlood Banking: Donor selection & processing – page 3
75 Blood Banking MCQs on Donor selection & processing with answers and explanations.
A donation is repeatedly reactive for total anti-HBc, while HBsAg and HBV NAT are negative. What happens to the unit?
Units repeatedly reactive for anti-HBc cannot be used for transfusion, because the donor may have occult HBV infection. Negative HBsAg and NAT do not overrule this.
A donor screening immunoassay is initially reactive. What is the next step?
An initially reactive result is repeated in duplicate on the same sample. If either repeat is reactive, the result is repeatedly reactive and the unit is discarded; otherwise it is considered negative.
Which mosquito-borne virus is screened by NAT on blood donations in the United States?
West Nile virus NAT has been required for US donations since 2003, with individual-donation testing when local activity is high. Dengue and chikungunya are not routinely screened there.
Why is the first 30–40 mL of blood diverted into a separate pouch during collection?
The first blood may carry a core of skin with bacteria. Diverting it into a pouch, which is then used for test samples, reduces platelet contamination.
What is the minimum interval between two plateletpheresis donations by the same donor?
Plateletpheresis donors may donate after at least 2 days, but no more than twice in 7 days and up to 24 times a year. 56 days is the interval for whole blood.
After a double red cell (2-unit) apheresis donation, the donor must wait at least:
Losing two red cell units needs longer recovery, so the interval is 16 weeks. 8 weeks applies to one whole blood unit.
What is the minimum hemoglobin for a patient donating blood for autologous use?
Autologous donors need hemoglobin of at least 11 g/dL (hematocrit 33%). Allogeneic donors must meet higher limits such as 12.5 g/dL.
Preoperative autologous collection should be completed no later than how long before surgery?
The last autologous collection should be at least 72 hours before surgery so the patient's plasma volume can recover. Shorter gaps increase risk of hypovolemia.
Which confirmatory test must the transfusing facility perform on red cell units received from a blood supplier?
The transfusing facility confirms ABO group of every red cell unit and D type of units labelled D-negative. Weak D testing of units is not repeated.
A healthy long-distance runner has a regular pulse of 46 per minute. Other findings are normal. The donor:
The usual pulse range is 50–100 per minute, but a lower regular pulse in a healthy athlete is acceptable after evaluation. Bradycardia here is physiological, not disease.
Pathogen reduction of platelets with amotosalen and UVA light works by:
Amotosalen enters cells and binds DNA and RNA; UVA light forms cross-links that block replication. This also inactivates donor T cells, so it can replace irradiation for TA-GVHD prevention.
Under current US FDA rules, what is the minimum hemoglobin for an allogeneic whole blood donor?
FDA requires at least 12.5 g/dL (125 g/L) for female and 13.0 g/dL (130 g/L) for male donors. A single cut-off of 12.5 g/dL for all donors was the older rule.
A prospective donor got a tattoo 5 weeks ago at an unregulated parlour. Under current FDA guidance, the donor is deferred for:
FDA reduced the tattoo and piercing deferral from 12 months to 3 months, which covers the window period of transfusion-transmitted infections with current testing.
A US resident returns from a short holiday in a malaria-endemic area. She had no symptoms. Under current FDA guidance, she is deferred for:
Travelers to malaria-endemic areas who are not prior residents of such areas are deferred for 3 months after departure. Longer (3-year) deferrals apply to former residents and people who had malaria.
A donor had malaria 18 months ago and was successfully treated. What is the correct decision under FDA guidance?
A person diagnosed with malaria is deferred for 3 years after completing treatment and being symptom-free. Semi-immune people may carry low-level parasitemia for a long time.
A donor received 2 units of red cells after surgery 10 weeks ago. Under current FDA guidance, the donor:
Receipt of allogeneic blood components leads to a 3-month deferral in current FDA guidance (previously 12 months). At 10 weeks the donor must wait a little longer.
A donor who takes clopidogrel wants to give apheresis platelets. How long after the last dose may platelets be collected?
Clopidogrel irreversibly inhibits platelet ADP receptors, so apheresis platelet donors must wait 14 days. Whole blood donation is still allowed because red cells and plasma are unaffected.
In US areas at risk, blood donations are screened by nucleic acid testing for which tick-borne parasite?
Babesia microti is transmitted by Ixodes ticks and causes transfusion-transmitted babesiosis. FDA guidance requires NAT screening of donations in affected regions. T. cruzi is screened by antibody.
To reduce the risk of TRALI, plasma for transfusion is preferably collected from:
Most TRALI cases are caused by donor HLA or HNA antibodies, often formed during pregnancy. Using plasma from males or from women tested negative for HLA antibodies reduces TRALI.
Before a plateletpheresis collection, the donor's platelet count should generally be at least:
A pre-donation platelet count of at least 150 × 10^9/L (150,000/µL) is required so that the donor's count stays safe after collection.