Blood bank Flashcards
Donation interval: One unit of whole blood.
8 weeks.
Donation interval: A double unit of whole blood by apheresis.
16 weeks.
Reasons for a 12-month deferral from donation (Part 1).
Paying for sex. Receiving blood products, tissue, etc. Immune globulin for hepatitis B. Syphilis or gonorrhea. Mucous-membrane exposure to blood.
Reasons for a 12-month deferral from donation (Part 2).
Tattoos, piercings, etc. Residing with someone with viral hepatitis. Unlisted vaccines. Incarceration >72 hours. Sex with someone with HIV. Malaria-endemic area, travel to.
Reasons for a 3-year deferral from donation.
Residence in a malaria-endemic area.
Personal history of malaria.
Soriatane (acetretin).
Reasons for a 6-month deferral from donation.
Avodart (dutaseride).
Donor requirements: Body temperature.
No more than 37.5 degrees C.
Donor requirements: Blood pressure.
No more than 180 over no more than 100.
Donor requirements: Hemoglobin and hematocrit.
At least 12.5 g/dL or 38%.
Autologous donation: Requirements.
Physician’s order.
Hemoglobin at least 11 g/dL or Hct at least 33%.
No risk of bacteremia.
When, relative to surgery, is autologous blood collected?
At least 72 hours before the operation.
Introduction of unused autologous blood into the general inventory.
Not allowed.
Plasmapheresis: Minimum weight of donor.
50 kg.
Plasmapheresis: Donation interval for typical donors.
4 weeks.
Plasmapheresis: Donation interval for frequent donors.
No more than twice a week.
At least 2 days between donations.
Plasmapheresis: How much whole blood may be removed?
Up to 500 mL (600 mL if donor weighs at least 80 kg).
Platelet-pheresis: Donation interval.
No more than twice a week.
At least 2 days between donations.
No more than 24 times a year.
Platelet-pheresis: Required platelet count.
150,000/μL.
Introduction of blood from a hemochromatosis patient (therapeutic phlebotomy) into the general blood supply.
The patient can have no medical conditions that would disqualify any allogeneic donor.
The unit must be labeled with the patient’s condition.
What happens when testing of a unit of autologous blood yields abnormal results?
The patient and the patient’s physician must be notified.
How to prevent bacterial contamination of platelets during collection.
Use a diversion pouch to collect the first 30 mL of whole blood and the skin plug.
Volume of whole blood drawn for donation:
A. Maximum.
B. Time limit.
A. 10.5 mL/kg.
B. 15 minutes.
Typical volume of whole blood drawn for donation.
Depending on the system:
450 ± 45 mL
- or -
500 mL ± 50 mL.
Definition of low-volume unit of whole blood.
Depending on the system:
300-404 mL or 333-449 mL.
Testing for weak D:
A. When?
B. How?
A. When there is no reaction of the donor’s red cells with the anti-D reagent.
B. Prolonged incubation and use of antihuman globulin.
How to label a unit found to have weak D.
As Rh positive.
Confirmatory blood grouping to be done at the blood bank upon receipt of new units of red cells.
ABO and Rh.
Confirmation of weak D is not required.
Screening for infectious diseases: Required tests.
Anti-HBc. HBsAg. Anti-HCV. HCV RNA. Anti-HIV. HIV RNA. Anti-HTLV1 and anti-HTLV2. RPR.
Screening for infectious diseases: Two agents for which testing is often done although not mandated.
West Nile virus.
Trypanosoma cruzi.
Screening for infectious diseases: Omission of testing requires ___ (4).
Approval of the medical director of the donor center.
Approval of the medical director of the transfusion service.
Labeling of the unit to indicate the omission.
Completion of testing as soon as possible.
Screening for infectious diseases: Directed apheresis donors and autologous donors.
Initially and every 30 days.
Obtaining a new pretransfusion sample in a known patient:
A. In whom is it required?
B. When is the sample taken?
A. In anyone who has been transfused or pregnant within the past 3 months.
B. No more than 72 hours before the transfusion.
After a transfusion, what must be retained for 7 days?
The pretransfusion blood sample.
A tube segment from the transfused unit.
Testing for weak D in a recipient.
Not required.
Antibody screen: Number of clinically significant antibodies that must be represented.
18.
Antibody screen: Phases of testing.
Immediate spin.
Incubation at 37 degrees.
Incubation with antihuman globulin.
Autocontrol:
A. Definition.
B. When used.
A. The incubation of the donor’s serum or plasma with the donor’s red cells.
B. With the antibody panel.
Why is it important to compare the results of pretransfusion testing with records of previous results (3)?
To avoid errors in patient identification.
To avoid sample mix-ups.
To be aware of previous antibodies, such as anti-Kidd, that can become undetectable.
Computer crossmatch: Requirements.
Negative antibody screen.
Validated computer system.
At least two previous determinations of ABO and Rh group.
Immediate-spin crossmatch vs. full crossmatch.
Full crossmatch
− Includes incubation with antihuman globulin.
− Required if clinically significant alloantibodies are detected in the immediate-spin phase.
Crossmatch in neonatal recipients: When not required.
When the neonate is <4 months old and there are no clinically significant maternal antibodies.
Giving Rh-positive platelets to an Rh-negative recipient.
Should be avoided if possible; otherwise, RhIg should be offered.
Rh-positive recipient <4 months old: First choice of RBCs.
O positive.
CMV negative.
Irradiated.
Rh-positive recipient <4 months old: Second choice of RBCs.
O negative.
CMV negative.
Irradiated.
Rh-negative recipient <4 months old: First choice of RBCs.
O negative.
CMV negative.
Irradiated.
Rh-negative recipient <4 months old: Second choice of RBCs.
Type specific.
CMV negative.
Irradiated.
Any recipient <4 months old: First and second choices of plasma.
First choice: AB.
Second choice: Type specific.
Any recipient >4 months old: First and second choices of plasma.
First choice: Type specific.
Second choice: AB.
Standard filter:
A. Size of pore.
B. Policy regarding reuse.
A. 170 μm.
B. May be reused for many times within 4 hours.
Standard filter: Use in leukocyte reduction.
Cannot be used for leukocyte reduction.
Can be omitted if a proper leukocyte-reduction filter is in place.
Fluids that may be infused in the same line as the red-cell unit.
Normal saline.
FDA-approved crystalloids.
No lactated Ringer’s solution, no dextrose solutions.
Transfusion:
A. Period of observation.
B. Infusion rate.
A. For the first 15 minutes of the transfusion.
B. 2 mL/minute.
Transfusion: When to take vital signs.
At 0 minutes, 15 minutes, and the completion of the transfusion.
Transfusion: Duration.
May last up to 4 hours but is usually completed within 90 minutes.
Causes of a positive autocontrol (3).
Autoantibody.
Antibody to previous transfused red cells.
Drug-induced positive DAT.
Antigens whose reactivity are enhanced by enzymes.
ABO, Lewis, I/i, P.
Rh.
Kidd.
Antigens whose reactivity is abolished by enzymes.
MNS.
Duffy.
Lutheran.
Titer at which cold-reacting IgM antibodies may be clinically significant.
1 : 1000.
Causes of a complex pattern of reactivity on an antibody panel (6).
Multiple antibodies. Antibody showing dosage. Antibody to antigens of high incidence. Antibody to antigens of low incidence. Polyagglutination. Antibody to a reagent.
High-titer, low-avidity antibodies: When to suspect their presence.
When there is a weak reaction with all cells of the antibody panel at the AHG phase.
High-titer, low-avidity antibodies: Specificities of clinically significant ones.
Yt-a.
Gy, Hy (members of the Dombrock system).
High-titer, low-avidity antibodies: Significance of “insignificant” ones.
They may mask significant alloantibodies.
Antibody to a reagent: When to suspect its presence.
When there is reactivity with all cells of the antibody panel.
Antibody to a reagent: How to circumvent it (4).
Use a different lot of reagent.
Use a different enhancement medium.
Wash the test cells.
If using a solid or gel medium, perform the tests in a test tube.
Antibody to a low-incidence antigen: When to suspect its presence.
When there is a reaction with one cell in the antibody panel.
T-activation: Examples of antigens subject to it.
T, Tk, Tn, Cad.
T-activation: Cause.
Bacterial neuraminidase exposes cryptic antigens on red cells.
T-activation: Specific causes.
Streptococcus pneumoniae: Atypical hemolytic-uremic syndrome.
Clostridium: Necrotizing enterocolitis.
T-activation: Detection (2).
Agglutination of affected red cells by adult serum but not by cord serum.
Arachis hypogaea.
T-activation: Clinical significance.
Transfusion of adult plasma (which contains natural anti-T antibodies) into affected infants can cause intravascular hemolysis.
T-activation: Treatment.
Give washed or plasma-poor blood products.
T-activation: Duration.
Resolves with the inciting infection.
Methods of elution.
Heat.
Acid.
Freeze-thaw method.
Digitonin.
Auto-adsorption:
A. Purpose.
B. Agent.
A. To remove autoantibodies from red cells so that any clinically significant alloantibodies can be detected.
B. ZZAP.
Auto-adsorption:
A. When it cannot be used.
B. Alternate technique.
A. In anyone who has been transfused or pregnant within the past 3 months.
B. Alloadsorption.
Hemagglutinin inhibition: Agent.
Neutralizing substance.
What neutralizes Sd-a?
The urine of guinea pigs.
What neutralizes the P antigen?
Pigeon eggs.
Hydatid-cyst fluid.
What neutralizes H substance?
Saliva.
What neutralizes Chido / Rodgers antigens?
Plasma.
What neutralizes Le-a substance?
Saliva.
Lectin: A1.
Dolichos biflorus.
Lectin: B.
Bandeirea simplicifolia.
Lectin: H.
Ulex europaeus.
Lectin: N.
Vicea graminea.
Antigen frequency: D.
85%.
Antigen frequency: C.
70%.
Antigen frequency: c.
80%.
Antigen frequency: Cw.
2%.
Antigen frequency: E.
30%.
Antigen frequency: e.
98%.
Antigen frequency: G.
84%.
Antigen frequency: f.
65%.
Antigen frequency: V.
1%.
Antigen frequency: K.
9%.
Antigen frequency: k.
99.8%.
Antigen frequency: Jk-a.
75%.
Antigen frequency: Jk-b.
75%.
Antigen frequency: Kp-a.
2%.
Antigen frequency: Js-a.
Whites: 0.1%.
Blacks: 20%.
Antigen frequency: Fy-a.
Whites: 65%.
Blacks: 10%.
Antigen frequency: Fy-b.
Whites: 83%.
Blacks: 20%.
Antigen frequency: M.
80%.
Antigen frequency: N.
72%.
Antigen frequency: S.
55%.
Antigen frequency: s.
90%.
Antigen frequency: U.
Whites: 99.9%.
Blacks: 99%.
Antigen frequency: P1.
80%.
Causes of a positive crossmatch: Negative antibody screen (4).
ABO mismatch.
Passively acquired ABO antibodies.
Anti-A₁.
Antibody to a low-incidence antigen.
Interpretation (3): 4+ reaction with anti-D reagent, 2+ reaction with D+ test cells.
Anti-LW.
Partial D.
Autoantibody with specificity for Rh.
B(A) phenotype:
A. Cause.
B. Recognition.
A. Production of a small amount of A substance on group B cells.
B. Forward phase: Weak reaction with anti-A reagent.
Reverse phase: As expected for group B.
Acquired-B phenotype:
A. Causes.
B. Recognition.
A. Persistent bacteremia, esp. bowel obstruction, bowel carcinoma, Gram-negative sepsis.
B. Forward phase: Weak reaction with anti-B reagent.
Reverse phase: As expected for group A.
Acquired-B phenotype: Confirmation (5).
Use a different manufacturer’s anti-B reagent.
Reacetylate the patient’s red cells.
Observe lack of reaction with acidified human anti-B.
Observe reaction with the patient’s own anti-B.
Observe absence of B substance in patient’s saliva.
Antibodies to A₁: Incidence (2).
A₂: 1-8%.
A₂B: 22-35%.
Antibodies to A₁: Clinical significance.
Usually none, unless reactive at 37 degrees.
Antibodies to A₁: Recognition.
Forward phase: As expected for group A or AB.
Reverse phase: Weak reaction with A test cells.
Interpretation: Weak reactivity with all cells in the panel at the AHG phase only.
Antibody to a high-titer, low-avidity antigen such as Chido / Rodgers.
Interpretation: Reactivity with all cells in the panel and the autocontrol, but only in the AHG phase.
Warm autoantibody.
Interpretation: Reactivity with all cells in the panel and the autocontrol in the immediate-spin phase.
Cold autoantibody.
Interpretation: Reactivity with all cells in the panel and the autocontrol at the immediate spin and at 37 degrees.
Cold autoantibody with a very broad thermal amplitude.
Effect of some hematolymphoid neoplasms on ABO testing.
Weakened expression of A or B antigen on red cells.
Effect of some gastric adenocarcinomas on ABO testing.
Excess free ABO antigens neutralize the anti-A and anti-B reagents, giving a false impression of group O.
Interpretation of a positive DAT:
A. With anti-IgG and anti-C3.
B. With IgG only.
C. With C3 only.
A, B. Probable warm autoantibody.
C. Probable cold autoantibody.
Positive DAT with anti-IgG: Next step.
Use elution or adsorption to look for any masked alloantibodies.
Causes of a positive DAT other than primary autoimmunity.
Neonatal: Passive transfer of antibodies, HDN, RhIg.
ABO-incompatible bone-marrow transplant.
Recent transfusion.
Drugs.
Antithymocyte globulin for transplant of solid organ.
When an autoantibody is suspected, what is the very next step?
To determine whether the patient is hemolyzing.
Warm autoantibodies: Significance of a positive anti-C3.
Its presence and strength correlate with the likelihood of hemolysis.
Warm autoantibodies: Guidance concerning transfusion.
Avoid if at all possible; otherwise, use techniques to unmask any clinically significant alloantibodies.
Benign cold autoantibodies: Thermal amplitude.
4-22 degrees, reacting best at 4 degrees.
Common types of benign cold agglutinin.
Anti-I in adults.
Anti-i in children.
Anti-H.
Benign vs. pathological cold agglutinins: Titers.
At 4 degrees C
Benign: 1 to 64.
Pathologic: 1 to 1000.
Primary cold autoimmune hemolytic anemia:
A. Synonym.
B. Typical patient.
A. Cold-agglutinin syndrome.
B. Elderly person with acrocyanosis and Raynaud’s phenomenon.
Primary cold autoimmune hemolytic anemia:
A. Type of hemolysis.
B. Type of antibody.
A. Intravascular, moderate.
B. IgM anti-I or anti-i.
Secondary cold autoimmune hemolytic anemia: Types (3).
Anti-I due to Mycoplasma pneumoniae.
Anti-i due to infectious mononucleosis.
Anti-I due to lymphoproliferative disorder.
Mixed autoantibodies: Classes.
Cold-reacting IgM and warm-reacting IgG.
Mixed autoantibodies: Specificity.
No consistent specificity.
Mixed autoantibodies: Clinical presentation.
Acute hemolytic anemia, sometimes associated with lupus.
Paroxysmal cold hemoglobinuria: Typical patient.
Child with viral infection or otitis media.
Paroxysmal cold hemoglobinuria: Clinical presentation.
Exposure to cold leads to hemolytic anemia with fever, chills, pain, jaundice, hemoglobinuria.
Paroxysmal cold hemoglobinuria: Degree of anemia.
Usually severe.
Paroxysmal cold hemoglobinuria: Treatment.
Keeping the patient warm and giving transfusions as needed.
Paroxysmal cold hemoglobinuria: Antibody and its specificity.
IgG anti-P.
Paroxysmal cold hemoglobinuria: DAT.
Positive with anti-C3 reagent only.
Paroxysmal cold hemoglobinuria: The Donath-Landsteiner test.
Blood incubated at 4 degrees and then at 37 degrees shows hemolysis.
How to keep cold autoantibodies from interfering with tests for alloantibodies (3).
Perform all tests at 37 degrees.
Use only monoclonal anti-IgG in the AHG phase.
Adsorption.
Mechanisms of drug-induced positive DAT.
Hapten.
Autoimmune induction.
Non-immune adsorption.
Drug-dependent antibody.
Hapten mechanism: Location of hemolysis.
Intravascular.
Hapten mechanism: Prototypical agent.
Penicillin.
Hapten mechanism: Diagnosis.
Incubation of serum and eluate with drug-treated and untreated red cells.
Drug-dependent-antibody mechanism: Location of hemolysis.
Extravascular.
Drug-dependent-antibody mechanism: Prototypical agents.
Piperacillin.
Cephalosporins.
Drug-dependent-antibody mechanism: DAT.
Positive with anti-C3 (complement-mediated hemolysis) and possibly with anti-IgG also.
Autoimmune induction: Effect of withdrawal of offending drug.
Autoimmunity persists but may subside with prolonged withdrawal of the drug.
Autoimmune induction: Prototypical agents.
Methyldopa.
Levodopa.
Procainamide.
Fludarabine.
2nd- and 3rd-generation cephalosporins.
Autoimmune induction: Diagnosis.
Autoantibody indistinguishable from those that of idiopathic WAIHA.
Non-immune adsorption: Mechanism.
A drug causes nonspecific binding of antibody onto red cells.
Non-immune adsorption: Prototypical agent.
Cephalothin (Keflin).
Non-immune adsorption: Diagnosis.
Positive antibody screen, positive DAT.
Negative eluate.
Transfusion in sickle-cell disease: Endpoint.
Reduction of concentration of HbS below
50% in adults.
30% in children.
Transfusion in sickle-cell disease: ASPEN syndrome.
Association of sickle-cell disease with priapism, exchange transfusion, and neurological events.
Occurs within 11 days after exchange transfusion.
Transfusion in sickle-cell disease: Specificities of most common antibodies.
K, C, E, Fy-a, Jk-b.
Transfusion in sickle-cell disease: Rate of alloimmunization per unit of phenotypically
A. Unmatched blood.
B. Matched blood.
A. 3%.
B. 0.5%.
Class I hemorrhage: Amount.
<15% of blood volume (750 mL).
Class II hemorrhage:
A. Amount.
B. Treatment.
A. 15-30% of blood volume.
B. Fluid resuscitation usually suffices.
Class III hemorrhage:
A. Amount.
B. Treatment.
A. 30-40% of blood volume.
B. Fluid resuscitation first; transfusion usually necessary.
Class IV hemorrhage:
A. Amount.
B. Treatment.
A. >40% of blood volume.
B. Fluid resuscitation first; transfusion necessary.
When to switch from fluid resuscitation to transfusion when treating a hemorrhage.
When 30 mL/kg (about 2 L) fluid have been given.