Bloodbank exam 3 study guide

cold antibodies

typically IgM (does not cross placenta). React best at room temperature or during IS crossmatching. Can sometimes appear at 37. generally not clinically significant. usually result in positive autocontrol and positive DAT

examples of cold allo:p1, M, N. cold auto: I, H, IH

warm antibodies

usually IgG (can cross placenta) react best of 37 or AHG. clinically significant and associated with hemolytic transfusion reactions and HDFN. reacts with autocontrol. Most are directed to the Rh system (e antigen)

what happens if you have autoimmune hemolytic anemia?

autoantibodies are present which leads to hemolysis. can be classified as warm or cold! positive autocontrol, positive DAT. elution used when DAT positive or adsorption used to remove autoantibodies to detect underlying alloantibodies. can be idiopathic or as a result of a known disease or drug.

differences of polyspecific AHG vs monospecific AHG

polyspecific contains antibodies against both IgG and components of complement (C3d). pos reaction with poly indicates that either IgG, complement or both is coating RBCs. Can confirm presence of in vivo coating but does not identify which specific component is responsible

monospecific contains antibodies for a single class. anti IgG AHG will only detect IgG and anti-C3 AHG will only detect complement components. monospecific is used to further investigate positive DAT with polyspecific. can also be used to avoid reactivity from cold autoantibodies

antibody screen

test used to detect unexpected antibodies in a patient’s plasma or serum. If present, usually as a result of RBC stimulation through previous transfusion or HDFN.

Performed for pts needing transfusion, pregnant women, plasma/ blood donors, pts w/ previous transfusion reactions, and as a part of prenatal testing to identify D-negative women who are candidates for RhIG

positive indicates the presence of unexpected antibody but not the specific antibody. if positive result, must do antibody panel.

delayed transfusion reaction

adverse reaction to blood transfusion that manifests some time after the transfusion has been completed that manifests days to weeks after. can be detected through antibody screen and panels. mixed RBC populations from previous transfusions can remain for up to 3 months

anti-I

IgM (cold). reacts on IS or room temp, can sometimes react at 37. common and reacts with all reagent, self and donor RBCs which results in positive autocontrol and DAT. generally considered not clinically significant. directed against a high-frequency antigen. naturalization can be performed to avoid reactivity. variable expression on RBCs and stronger on cord blood cells. Rabit erythrocyte stroma (RESt) adsorption can be used to remove cold antibodies. reciprocal relationship to i

anti-i

cold antibody, IgM. newborn RBCs are typically rich in i antigen and have little I antigen. Anti-i is more prevalent on cord blood cells. lower frequency in adults. reciprocal relationship to I

autoabsorption

technique used to cleave autoantibodies from serum to detect underlying alloantibodies.

Serum is incubated in pts own RBCs under specific binding temps (cold vs warm), all RBCS are removed since they are coated with autoantibodies which leaves behind serum that can be used for further antibody identification. can be used for both cold and warm

should not be used if pt has been recently transfused

neutralization

technique used to avoid reactions caused by cold antibodies (anti-p1, anti-M, anti-N). inhibits the reactivity of these antibodies in serum. goal is to unmask presence of other, potentially clinically significant antibodies.

procedure includes adding a substance that contains soluble form of the antigen. when pt serum is mixed with this substance, the soluble antigen binds to the antibody which blocks its ability to react. important to use a control.

enzyme pretreatment

technique used to determine specificity of unexpected antibodies in pt serum. Modification of antigens on the surface of the reagent RBCs. Treat reagent RBCs from antibody panel w/ proteolytic enzymes such as ficin, papin and bromelin. These cleave glycoproteins from RBC surface which alters the reactivity of some antigens while enhancing others. Known to destroy Duffys (Fy) and MNS. Enhances Rh, Kidd (Jk), Lewis (Le), and P2. Kells can be enhanced using DTT

there is a 2 stage (indirect) and 1 stage (direct method)

elution

technique used to remove antibodies. important when DAT is positive. used to identify the specificity of antibody and investigate suspected cases of HDFN. also used to demonstrate presence of anti- D antibody when D-antigen sites are blocked leading to false-neg D typing.

mechanism includes multiple washing steps, different techniques include lowering the pH, physical methods (heat, freeze, thaw), or using organic solvents

how many days must you wait to type a patient that has been given blood?

3 months

characteristics of the Rh system antibodies

clinically significant! Can cross placenta (IgG) warm antibodies

anti-D, anti-C, anti-c, anti-E, anti-e. can cause HDFN

Rh HDFN is most severe. detected through antibody screen, if positive, teste through antibody panel. enzyme pretreatment enhances reactivity of Rh antibodies

RhIG rules

D-negative pregnant women, negative antibody screen, fetus is D-positive

what do enzymes do to Rh antibodies?

enzymes enhance the reactivity of Rh antibodies. ficin, papain, trypsin and bromelin. this enhancement is useful to aid in the detection and identification of Rh antibodies.

what does it mean if an antibody is detected in immediate spin?

this is a cold antibody, IgM

Anti-Le, Anti-M, Anti-N, Anti-I, Anti-P1 (lewis, MNS, P1)

usually clinically insignificant

crossmatch procedure

critical part of compatibility testing used to detect in-vitro

serves as double check of ABO btwn donor and recipient

provides second means of detecting clinically significant antibodies

includes- immediate spin which can expose cold antibodies,

incubation at 37 (enhancement media for everything but anti-D) , following enhancement and wash steps, AHG is added and centrifuged. Agglutination indicates clinically significant IgG warm antibodies. check cells confirm all negative tubes

what to do if you get an incompatible unit?

do not transfuse into patient! investigate cause of incompaitbility.could be due to unexpected antibody. review previous blood bank records, repeat ABO and Rh typing, perform antibody panel, autocontrol and DAT test. if DAT is positive, perform elution.

infant (4mo) compatibility testing

ABO and D typing must be performed on infant blood sample. reverse typing is not routine since they could be from mom. antibody screen can be performed from infant or mom but maternal is preferred. if antibody is present, antigen- negative donor must be selected for transfusion.

what blood type is used for exchange transfusion when mom has a circulating atypical antibody?

newborns ABO and D type is determined. identify maternal atypical antibody. select ABO and D compatible blood. crossmatch compatibility testing must be performed

requirements: RBCs less than 7 days old, resuspended in group AB FFP, CMV reduced risk components, irradiated to prevent graft vs host disease, hemoglobin S- negative

In the process of identifying an antibody panel, the technologist saw 2+ reaction on 3 of the 10 on immediate spin. The reactions disappeared at 37 and did not come back

anti- Lewis a

post transfusion antigen typing restrictions

if units are compatible but have antigens, must type patient for antigens

Interpretation of crossmatch data

if a 2+ reaction in anti-A occurs, this means there is an A antigen

Donor has something that patient does not. What should you do?

This donor is NOT compatible. Do not use this blood for this patient

Frequency: if 30% frequency, how many of 10 donors have this?

3 donors

Emergency release crossmatches

O neg is universal donor. In emergencies use O neg, but do not use when not necessary because true O neg patient can ONLY use O neg

What to do with positive antibody screen

this narrows down the potential antibodies! If screen 1 is only positive one then find the antibodies with only screen 1 positive, same for screen 2. All that do not have the same pattern are ruled out!

When we get our units from blood centers and all testing has been done, what should we do to get this blood in our inventory?

Retype 1 time

Mom has positive antibody screen, how do we choose the appropriate blood to give baby?

Mom has circling antibody so give something compatible with what mom has!

incidence

if low incidence, almost every cell will be 0. If high incidence, almost every cell will be +

example: k (cellano) is all + going down therefor it is low incidence