MLT219: Immunohematology. Week 4 Part 1 ABO Discrepancies Assignment
Due date:12/3/23 by 11:59 PM
Name:________Ricardo de Castro Garcia Franca______.______________________________
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This assignment is designed for the CPTC MLT Program.
Students are expected to complete their own work and must abide by the Student Code of Conduct and MLT Program Policies.
Grading:
This assignment is worth a total of 54 points. All assignments must be spell checked. USE YOUR TEXTBOOK TO SOLVE THESE
DISCREPANCIES. Not all will need resolution. If no resolution is required, state “N/A”. Otherwise, state the probable cause
of the discrepancy, validity of the result, and resolution. It would be helpful to highlight the focal areas. Patient six is
completed to use as an example.
An automatic 10% deduction in the assignment grade will be assessed for the following offenses:
 More than five typos included in the text document.
 Student’s name is not included within the text document OR student’s assignment is not saved with name included in the
text
An automatic zero will be assessed for the following offenses:
 Failure to follow directions for APA citation when necessary or plagiarism. ANSWERS MUST BE IN OWN WORDS.
 Assignment not completed in full
ABO Discrepancies
An ABO discrepancy is a situation in which reactions obtained in the forward type DO NOT correlate with reactions obtained in the reverse type.
There are two types of reactions, unexpected positives and unexpected negatives.
For example, no agglutination of the patient RBCs with anti-A and anti-B indicates the patient is group O. The expectation then is that both the
A1 and B reagent cells will be agglutinated by the patient’s serum due to the expectation of anti-A and anti-B being present in the patient’s
serum or plasma. If negative reactions occur with either reagent cell, then an ABO discrepancy has occurred. No blood may be transfused until
the ABO discrepancy has been resolved. If the need for blood products is urgent, the technician may need to consult with the patient’s physician
and the pathologist. The type of discrepancy involved will determine how the situation should be handled. In most situations group O blood
may be transfused while the discrepancy is being investigated.
The FIRST course of action to resolve an ABO discrepancy is to REPEAT the forward and reverse type. If the same discrepant results are
obtained it must be determined whether the problem lies with the RBCs or the serum.
MLT219: Immunohematology. Week 4 Part 1 ABO Discrepancies Assignment
Due date:12/3/23 by 11:59 PM
Problem
Unexpected positive
in reverse type.
Causes and Factors to
Consider
Forward types as Group A
but reaction, usually weak,
with A1 reverse cells.
Subgroup of A with anti-A1
Strong cold auto-agglutinin
Rouleaux – examine
microscopically
Unexpected negative
in reverse type.
Unexpected antibody
present
Low antibody level due to
being elderly, an infant or
immunocompromised.
Patient RBCs heavily coated
with protein.
Weak subgroup of A or B.
Resolution
Test patient cells with anti-A1 lectin should be negative.
Test patient serum or plasma with A2 cells should be negative.
Cold agglutinin titer to identify anti-I.
Autoabsorption to remove anti-I
Prewarmed technique to eliminate false positive in compatibility tests.
Saline replacement technique
*Spin tubes
*Remove serum
*Add 3 drops saline, mix
*Spin and read.
*Should be negative
Perform antibody identification.
Incubate reverse at RT for 15-30 minutes, respin.
If still negative incubate at 4°C for 15-30 minutes with an autocontrol.
Unexpected positive
Perform Direct Antiglobulin Test – will be discussed later in the course.
in forward type.
Unexpected negative
Incubate at RT for 15-30 minutes.
in forward type.
May have to do higher level testing which will be discussed later in this course.
NOTE: This chart illustrates the most common causes, there are many other situations, which may occur which, will be covered later in
this course.
MLT219: Immunohematology. Week 4 Part 1 ABO Discrepancies Assignment
Due date:12/3/23 by 11:59 PM
No.
Patient’s
Name
ABO
Rh
Anti
-A
Anti
-B
Anti
-D
Rh
ctl
1
One,
Patient
AB
Pos
4+
4+
4+
2+
ABO Discrepancies
Weak CCC Weak CCC
D
D ctl
A1
cells
B
cells
2+
2+
Valid result?
Why (what is
missing/
Wrong)
(2 pts per)
No.
The Rh
control is 2+
positive in
the AB +
blood. There
is no
negative
control in the
forward
reaction
(invalid test).
Also, in the
reverse
typing A1
cells and B
cells are 2+
Possible
cause?
(2 pts per)
Agglutination
with 2+ on
A1 cells and
B cell could
be an
indication of
rouleaux
formation
Resolution
(2 pts per)
Run a DAT
Microscopic
examination.
Saline
replacement test.
Incubate the
sample at 37°C
for 15 min, then
washed with
saline and repeat
the typing.
MLT219: Immunohematology. Week 4 Part 1 ABO Discrepancies Assignment
Due date:12/3/23 by 11:59 PM
2
Two,
Patient
A
Pos
4+
0+
4+
2+
4+
3
Three,
Patient
O
Pos
0
0
4+
0
0
Four,
Patient
AB
4
NoThe reverse
typing shows
2+ on A1
cells
NoNegative
results on
the reverse
typing for A1
cells and B
cells
Pos
4+
4+
4+
Ø
0
0
NoThe Rh
control test
is missing.
Subgroup of
A with A1
cold
autoantibody
reacting with
A1 cells
Test the patient
cells with
Dolichos biflorus.
It will agglutinate
cells of the A1
but not the A2
phenotype.
Elderly
patients with
antibodies.
bellow level
of
detectability.
Newborn
patients
Enhance the
weak or missing
reaction by
incubating the
patient serum at
room
temperature for
15 minutes.
Erroneously
omitted.
Perform the Rh
control
Lack of
negative
control on
the forward
typing
5
Five,
Patient
A
Neg
4+
0
0
2+
2+
0
4+
No-
Something is
coating the
Note “A negative
D control will
verify that the
patient RBCs are
NOT
spontaneously
agglutinating”
Wash patient
cells with warm
MLT219: Immunohematology. Week 4 Part 1 ABO Discrepancies Assignment
Due date:12/3/23 by 11:59 PM
Weak D
control is 2+
6
Six,
Patient
(Ex)
O
Pos
0
0
0
7
Seven,
Patient
B
Neg
0
4+
0
8
Eight,
Patient
AB
Pos
4+
4+
4+
Ø
0
4+
4+
No- must
prove Rh
status
4+
2+
NoThe reverse
typing shows
2+ on the B
cells
1+
0
NoThe reverse
typing shows
1+ on the A
cells
patient’s
cells in-vivo.
Spontaneous
agglutination
of antibodycoated cells
saline and repeat
the test.
Patient has
weakened
expression of
D antigen or
patient is
truly D
negative.
The reaction
with B cells in
reverse type
can be due
to cold
autoantibody
(reacting
with I
antigen on B
cells. )
WEAK D test
A2B
subgroup
individuals,
who can
produce
naturally
occurring
anti-A1
antibody
Run DAT and
auto control
Wash patient
cells with warm
saline and repeat
the test.
Run DAT and
auto control
Test cells with
anti-A1 lectin.
Anti-A1 lectin
agglutinates A1
(or A1B) cells but
does not
agglutinate A2
(or A2B cells)
MLT219: Immunohematology. Week 4 Part 1 ABO Discrepancies Assignment
Due date:12/3/23 by 11:59 PM
Run an auto
control.
9
10
Nine,
Patient
Ten,
Patient
AB
B
Neg
Pos
4+
0
4+
4+
0
0
0
Ø
4+
2+
0
0
2+
2+
0
4+
1+
NoThe reverse
typing shows
1+ on the B
cells
0
NoB+ blood
type with
Anti-D
negative test
result.
It -must
prove Rh
status
Possible cold
reacting
antibody
against some
antigen on
the B cells
Run an antibody
screen and panel.
Patient has
weakened
expression of
D antigen or
patient is
truly D
negative
Perform a weak
D test, incubating
at 37C for 15
min.
Antibody
identification.