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50 Cards in this Set
- Front
- Back
How much will one unit RBCs raise the hgb & hct?
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Hgb: 1 g/dl
Hct: 3% |
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How much will one unit plts raise the count?
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30-60,000
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What are the indications for washing / leukocyte reduction?
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1. Risk CMV viremia
2. Decreased formation HLA antibodies 3. Pts with recurrent FNHTR |
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Should platelets be ABO and Rh matched?
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Yes.
ABO is on platelets (but low density... usu ok if "plasma compatible") Rh is NOT on platelets but there are some residual RBCs |
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Universal donor?
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RBCs: O
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Components of cryo?
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vWF, factor VIII, factor XIII, fibronectin, fibrinogen
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Components of FFP?
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Factor 2,5,10,11... and all factors
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Uses of FFP
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Liver disease
Coagulopathy Warfarin reversal Vit K def (PT:PTT > 1.5x nl) |
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Uses of cryo
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DIC (only product with fibrinogen, f'gen<100)
vWF deficiency factor 13 deficiency can be used in hemophilia A (some factor 8) but not first line HAS ABO ANTIBODIES |
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How old do you have to be to donate blood?
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16
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Minimum hgb & hct for blood donation
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12.5 & 38%
11 & 33% for autologous |
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Temperature, pulse, and bp requirements for donation?
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Max temp 37.5
HR 50-100 bp < 180/100 |
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How much whole blood should be drawn?
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450 +/- 45 mL
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Storage requirements after donation?
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1-6C if used for RBCs
20-24C if making other components first; must be stored at 1-6C within 8h for RBCs |
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Common donor reactions?
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Vasovagal: SLOW heart rate, syncope, nausea. Elevate feet.
Hypovolemia: FAST heart rate, " ". IV fluids. Hyperventilation Citrate effect (apheresis donors only): causes hypocalcemia - perioral tingling, arrhythmia, seizure. Slow infusion rate; oral Ca++ |
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What are the reasons for indefinite deferral from donating?
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- Viral hepatitis after age 11
- Parenteral drug use - Family hx CJD - Receipt of human dura or pituitary growth hormone - (+) HbsAG or anti-HBc - HCV - HTLV-1 - Travelers to CJD areas - Use of bovine insulin from UK - Hx of babesia or Chagas - Drug: Etretinate - Receiving money for drugs or sex |
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What testing is required for donor blood?
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ABO & Rh: Forward AND reverse typing of ABO. Rh type determined by anti-D (forward typing); if -, must test for weak D. Rh- when BOTH are negative.
Antibody screen: in donors with h/o pregnancy or transfusion Infxs dz: HbsAg, anti-HBc, anti-HCV, HCV RNA, anti-HTLV-1&2, anti-HIV-1&2& HIV RNA, RPR (syphilis), WNV |
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If a patient has been pregnant or transfused in the past 3 months, how close to the date of transfusion must a sample be drawn for testing?
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Within 3 days
Serum or plasma acceptable |
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How long must a sample be kept after transfusion?
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7 days
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What are the common "nuisance" alloantibodies?
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anti-M, N, Lewis, I, P.
usually detected at room temperature (many labs omit this step and only test at 37C) |
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Pt is A+. What is FORWARD type & REVERSE type?
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Anti-A: ++
Anti-B: - Anti-Rh: ++ A cells: - B cells: ++ (Forward: add antisera to pt blood. Reverse: add pt's sera to reagent RBCs) |
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What are the 3 columns we use for antibody screening?
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IS: immediate spin (usu nuisance antibodies; usu IgM)
37C: IgG clinically significant antibodies are warm-acting. Not that useful by itself. AHG: REQUIRED. antihuman globulin phase, aka "Coombs phase". anti-IgG is added to tube. Detects clinically significant abs. All should be negative;if (+) perform complete panel. (Rows are test cells with all impt antigens represented. All group O) |
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What alloantibody is notorious for becoming undetectable over time yet remaining clinically significant?
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KIDD! (Jka & Jkb)
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What is dosage effect and which antigens express it?
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Dosage effect: When an antibody reacts more strongly to homozygous cells than to heterozygous.
Seen in all Rh antibodies EXCEPT D Classically seen in Kidd, Duffy, Rh, MNS (Jka, Jkb, Fya, Fyb, DCEce, MNSs) (basically - seen in all except Lutheran, P, lewis, & Kell) |
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Do we crossmatch blood for infants?
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Not under 4 months old, unless clinically significant antibodies are detected (may use mom's serum)
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What is the purpose of crossmatching?
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Final check on issued blood
Aimed at detecting ABO incompatibility Performed at room temp ("immediate spin crossmatch); if clinically significant alloantibodies present - must do AHG phase. |
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What are the carbohydrate antigens?
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ABO, Le, I, M, N, P
Naturally occurring antibodies (usu IgM; rx at room temp; agglutinating) |
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What are the protein antigens?
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All others!
Antibodies made only after exposure to products with an antigen (usu IgG; rx at 37C; "coating") |
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Describe the ABO antigens
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Carbohydrates
Genes encode for enzymes (glycosyltransferases) that trx saccharides onto H antigen base A&B genes on Chrom9 (O allele does not code fxnl enzyme; type 2 H chains fucosylated to H antigen) |
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How is A antigen different from B?
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A: N-acetyl-galactosamine
B: D-galactose |
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What is the Bombay phenotype?
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When h gene inherited instead of H. NO H SUBSTANCE PRODUCED.
Extremely rare Produce dangerous anti-H |
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Which blood groups have more H?
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O>>A2>B>A2B>A1>A1B
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What antibodies are present in blood group O?
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anti-A & anti-B
IgM & IgG |
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What types of blood group A are there?
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A1 & A2.
A1 cells have more A than A2 cells. 80% are A1; 20% A2. anti-A1 can be found in up to 5% ppl with A2, 35% A2B |
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What is the most common ABO blood type in whites? blacks?
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O (~50% each)
A (40%W, 25%B) B (10%; 20%) AB (5% each) |
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Rh nomenclature
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R1: DCe: 40%w, 15%b
R2: DcE: 10% ea R0: Dce: 5%w, 45%b*** Rz: DCE: rare r' : dCe: 3% ea r'' : dcE: rare r : dce: 40%w, 30%b ry : dCE: rare **note these are GENOTYPES. need 2 of the alleles. |
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Most common Rh- & Rh+ genotypes in wh & bl?
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Rh+ : R1/R1 (DCe) or R1/r (DCE/dce) in wh
R0/R0 (Dce/Dce) or R0/r (Dce/dce) in blacks Rh-: r/r (dce/dce) in BOTH ** R0 most common allele in bl (rare in wh) Rh- : r/r (dce/dce) |
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How does a weak D react with anti-D reagent?
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negative in IS
negative at 37C POSITIVE at AHG phase |
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What causes weak D phenotype?
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Quantitative WEAK D: most common. gene alteration, reduced D antigen expression
(common in bl - Dce haplotype (R0) - due to position of C) PARTIAL D: RBCs lack epitope(s) of D antigen. **partial-D women at risk of forming anti-D to D+ fetus |
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Does transfusion of weak D into D- pt result in immune response?
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Only if pt previously sensitized
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Do we test & label for weak D?
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We test DONOR samples for weak D
Labeled D+ if present Recipient not tested |
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What is Rh null?
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No Rh antigens
(no Rh or RhAG (Rh assoc glycoprotein) ** Lack LW, Fy5. Weakened S, s, U ** Structural abnormalities (stomatocytosis!) |
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What is the most immunogenic antigen that is non-ABO?
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D!
80% D- pts will develop anti-D after exposure to a single unit |
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What units should be selected for a patient with anti-E?
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E-negative, c-negative
This is because most ppl with antiE are R1/R1 (DCe/DCe) and have been transfused with R2 blood (DcE), thus acquiring an anti-E and anti-c. Anti-c is often too weak to detect but is a COMMON CAUSE OF DHTR. |
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RBCs are negatively charged... How can we get them closer together to speed up testing?
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Add a potentiator to the antibody screen at 37 & AHG phases
LISS, PEG, bovine albumin |
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When is adding anti-C3d helpful in the AHG phase of antibody screening? (as opposed to anti-IgG that is normally used)
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- C3d is a nonreactive byproduct of complement fixation on RBCs
- Anti-C3d is useful for evaluating IgM-related hemolysis and cold agglutinin disease, where antibodies are not usually detectable via anti-IgG |
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How are proteolytic enzymes used in pretransfusion testing, and what antigens do they affect?
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Cleave proteins on RBC surface, may make underlying antigens more available
Destroys some antigens (e.g., Duffy and MNS), enhances others (ABO, Rh, Jk) |
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What is adsorption?
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Removal of specific antibodies from sample via incubation with antigen-positive RBCs
Used to remove warm or cold autoantibodies (“autoadsorption”) from sample in order to detect underlying alloantibodies May also be used to remove one or more alloantibodies (“alloadsorption”) from sample in order to detect or confirm the presence of other alloantibodies e.g., Sample has anti-K, anti-C, and anti-S but anti-S isn’t visualized well. Use K+C+S– RBCs to adsorb the anti-K and anti-C and leave the anti-S in the “adsorbed serum” for clearer results |
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What is elution?
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Technique for removal of antibodies bound to RBC surface for analysis.
May be done with heat, cold, chemical (e.g., glycine) treatment |
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How is DTT/2ME used in pretransfusion testing?
Chloroquine? |
Dithiothreitol (DTT) or 2-mercaptoethanol (2-ME) denatures surface RBC antigens of multiple groups (including Kell, Lutheran, Dombrock, Yt, LW). Can also be used to remove IgM antibody activity from serum
Chloroquine removes IgG from coated (DAT-positive) RBCs to allow for accurate phenotyping (effective at least 80% of the time). Also removes residual HLA antigens from RBCs |