MMSC 420 Exam 1 with complete solution;2023 edition
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Course
MMSC 420
Institution
MMSC 420
MMSC 420 Exam 1 with complete solution;2023 edition
expected ABO typing results
forward and reverse typing results match
unexpected ABO typing results
-forward and reverse typing results do not match (extra reactions, missing reactions)
-current typing does not match historical records
pre-...
MMSC 420 Exam 1 with complete solution;2023 edition
expected ABO typing results
forward and reverse typing results match
unexpected ABO typing results
-forward and reverse typing results do not match (extra reactions, missing reactions)
-current typing does not match historical records
pre-analytical errors (ABO discrepancy)
errors occurring before patient sample is tested that lead to ABO discrepancy
-incorrect identification of patient
-incorrect labeling of specimen (labeling needs to occur at the patient bedside)
-patient's samples mixed up
analytical errors (ABO discrepancy)
errors that occur during testing that lead to ABO discrepancy
-technical errors
-clerical errors: mixing up tubes, writing down results incorrectly
-cell suspension too heavy: beyond 2-5% there is post zone effect
-failure to add reagent of patient serum
-failure to follow instructions or standard operating procedures: e.g. letting incubation go
too long
-failure to note hemolysis: always a positive reaction
-uncalibrated centrifuge
-contaminated reagents
-under/ over centrifugation
-improper resuspension of cell button: miss weak reactions
-confusing patient samples
post-analytical errors (ABO discrepancy)
things that were done in the hospital that lead to ABO discrepancies
-dilution of antibodies: administering plasma products causes patient's own plasma and
antibodies to become diluted and react weakly in reverse type
-exchange transfusion/ RBC transfusion: introducing RBCs that are not the same ABO
type as the patient cause forward typing to show 2 cell populations
-plasma expanders: administering albumin or crystalloids causes issues with ABO
typing
-bone marrow/ stem cell transplant: patient's ABO type might not fully convert and lead
to ABO typing discrepancies
determining cause of ABO discrepancies
-suspect weaker reactions: look at 1+ reactions, or missing reactions as the first sign of
an issue
-review patient's history: ongoing diagnoses, past treatments, or infections can help to
clue in what is going wrong
-suspect the serum: discrepancy issues are commonly due to weak reacting, or cold
reacting antibodies
group I ABO discrepancies
Unexpected reactions occur in the reverse type due to weakly reacting or missing
antibodies
, -most common type of ABO discrepancy
-forward typing is normal
-resolutions: RT or 4C incubation to enhance IgM ABO antibodies, increasing cell to
serum ratio (4 drops of patient serum instead of 2 to get more antibody in the mix), look
at patient history
group I ABO discrepancies causes
-inability/ decreased ability to produce antibodies: newborns up to 6 months, elderly,
leukemia or lymphoma with agammaglobulinemia, immunosuppressive therapies,
congenital hypogammaglobulinemia/ agammaglobulinemia, bone marrow transplant
recipients
-diluted antibodies: massive transfusion of plasma products dilutes patient's antibodies
-ABO subgroups (if antibodies are present)
group II ABO discrepancies
unexpected reactions in the forward typing due to weakly expressed or missing antigens
-reverse type is normal
-resolution: RT or 4 C incubation and enzyme enhancement to strengthen reactions of
antiseras with patient RBCs, look at patient history
group II ABO discrepancies causes
-2 cell populations: RBC transfusion/ exchange transfusions and chimerism (due to
bone marrow or stem cell transplant) lead to mixed field agglutination with antiseras
-polyagglutinable RBCs: react with all antiseras
-weakly expressed A or B antigen: old age or disease (hodkin's lymphoma, leukemia)
-ABO subgroups: react weakly with antiseras
-excess blood group soluble substance (BGSS): due to carcinoma of stomach or
pancreas, can neutralize reagent antiseras and appear completely negative (wash cells)
-fetal maternal bleeds
auto control and screening cells
if you run your ABO typing at room temperature or 4 C to enhance the reactions, you
will also have to run _________________ and _____________________ at the same
temperature
group III ABO discrepancies
unexpected reactions that occur due to abnormal plasma proteins
-rouleaux (coin stacking) is usually seen, and needs to be differentiated from true
agglutination (microscopically)
-resolution: saline replacement (replace plasma with drops of saline, if the cells disperse
it was rouleaux, if not it was true agglutination)
group III ABO discrepancies causes
-wharton's jelly: substance in cord blood that contaminates samples at delivery, wash
cells
-multiple myeloma
-waldenstrom's macroglobulinemia
-hodgkin's lymphoma
-elevated fibrinogen
-plasma expanders (albumin or crystalloids)
group IV ABO discrepancies
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