MMSC 420 Exam 1 Questions and Answers |
Latest 2026/2027 Update | Graded A+.
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
-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)
-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
-
Latest 2026/2027 Update | Graded A+.
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
-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)
-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
-
