ABO NCLE Exam Questions and Correct
Answers – Converted
Expected ABO typing results - ANSWER-forward and reverse typing
results match
unexpected ABO typing results - ANSWER--forward and reverse typing
results do not match (extra reactions, missing reactions)
-current typing does not match historical records
pre-analytical errors (ABO discrepancy) - ANSWER-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) -ANSWER-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) - ANSWER-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 - ANSWER--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 - ANSWER-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 - ANSWER--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 - ANSWER-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 - ANSWER--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 - ANSWER-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 - ANSWER-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 - ANSWER--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 - ANSWER-unexpected reactions due to
miscellaneous problems
-cold reacting autoantibodies
-cold reacting alloantibodies
-bone marrow transplant: patient's ABO type never fully converts and
forward and reverse type don't match
-ABO isoagglutinins
-antibody against low incidence antigen in antisera: positive reaction is
due to extra antibody in reagent antisera reacting with an antigen on the
patient RBC, not due to ABO antigen (test with another lot #)
A subgroups - ANSWER--A1: about 80% of type A individuals
-A2: about 20% of type A individuals, usually not detected unless anti-
A1 is produced and causes issues with reverse type
-weak A subtypes exist, but are extremely rare
A2 subgroup ABO discrepancy - ANSWER--if an individual is type A2
and produce anti-A1 the forward type looks like a normal A, but the
reverse type shows antibody against A1
Resolution:
Answers – Converted
Expected ABO typing results - ANSWER-forward and reverse typing
results match
unexpected ABO typing results - ANSWER--forward and reverse typing
results do not match (extra reactions, missing reactions)
-current typing does not match historical records
pre-analytical errors (ABO discrepancy) - ANSWER-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) -ANSWER-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) - ANSWER-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 - ANSWER--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 - ANSWER-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 - ANSWER--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 - ANSWER-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 - ANSWER--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 - ANSWER-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 - ANSWER-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 - ANSWER--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 - ANSWER-unexpected reactions due to
miscellaneous problems
-cold reacting autoantibodies
-cold reacting alloantibodies
-bone marrow transplant: patient's ABO type never fully converts and
forward and reverse type don't match
-ABO isoagglutinins
-antibody against low incidence antigen in antisera: positive reaction is
due to extra antibody in reagent antisera reacting with an antigen on the
patient RBC, not due to ABO antigen (test with another lot #)
A subgroups - ANSWER--A1: about 80% of type A individuals
-A2: about 20% of type A individuals, usually not detected unless anti-
A1 is produced and causes issues with reverse type
-weak A subtypes exist, but are extremely rare
A2 subgroup ABO discrepancy - ANSWER--if an individual is type A2
and produce anti-A1 the forward type looks like a normal A, but the
reverse type shows antibody against A1
Resolution:
