1. What is the course of action one must take when an ABO discrepancy is obtained?
Enumerate the steps.
First, identify the problem if it is due to problems with the patient’s serum(reverse typing),
problems with the patient’s RBC(forward typing), or problem with both serum and cells.
Second, check if it is a technical problem such as blood sample and test tube labelling
errors, failure to add reagents, or the addition of incorrect reagents/sample. Lastly, if the
discrepancy persist and appears to be due to an error in specimen collection or
identification, a new sample must be drawn from the patient and all RBC and serum testing
repeated.
2. What blood group and specific blood component may be transfused when there is no
enough time to resolve an ABO discrepancy?
Encountering such discrepancy, all results must be reported but the ABO type
interpretation must be delayed until the discrepancy is resolved. But for emergency cases,
like blood from a potential transfusion recipient, it may be necessary to administer group O,
Rh-compatible RBCs before the discrepancy is resolved.
3. Describe four problems and causes associated with ABO discrepancies.
Group 1 discrepancy. This type of discrepancy is most common compared to the other groups.
It is mainly seen in reverse grouping due to weak / missing antibodies. Some of the common
conditions associated with this type of discrepancy are: Newborns • Elderly patients • Patient
with Leukemia or Lymphoma • Patients on immunosuppressive drugs • Patients with
immunodeficiency diseases • Patients with bone marrow transplant
Resolution:
o
o
For newborns, only forward grouping is done till 4 months of age.
These discrepancies can be solved by enhancing the serum grouping reaction.
This can be achieved by incubating the cells serum mixture at low temperatures
(4 0C for 15-30 min) or by prolonging incubation at room temperature (½hr-1 hr
at 220C)
Group 2 discrepancy. This is due to missing or weak antigens. This type of discrepancy is
seen least commonly. The causes are: • Subgroups of A or B • Leukemia and Lymphoma •
Excess antigen of blood group soluble substances • Acquired A or B antigens.
Subgroups of A/B can be solved by:
o
o
o
o
Repeating blood grouping by using washed cells
Use of anti AB antisera and anti-A1 lectin
Adsorption elution
Similarly, subgroups of B are detected using O and polyclonal sera
Group 3 discrepancy. This is due to proteins or plasma abnormalities. The causes in this
group are: • Elevated levels of plasma globulins as seen in cases of Multiple Myeloma,
Waldenstrom's macroglobulinemia and Hodgkin's lymphoma • Elevated levels of fibrinogen •
Use of plasma expanders such as dextran • Wharton's jelly in cord blood samples
Resolution:
o
o
The main problem is due to Rouleaux formation, which is resolved by washing the cells
with normal saline 6-8 times, and confirming it with microscopic examination.
If the serum/reverse grouping is affected, perform saline replacement technique:
 Reagent cells and patient serum centrifuged to allow antigen and antibody to
react
 Serum is removed and replaced by an equal volume of saline (saline disperses
cells)
 Tube is mixed, centrifuged, and reexamined for agglutination
Group 4 discrepancy. Polyagglutination: this is due to exposure of hidden erythrocytes
antigens (T antigen in bacterial or viral infections) • Patient with cold auto antibodies • A2 or A2B
individual with anti A1 antibodies • Naturally occurring or irregular antibodies reacting at room
temperature • Cis-AB
Resolution:
o
Poly agglutination
 Symptoms suggestive of infection
 Auto control negative
 DAT negative
 Use of various lectins (Glycine soja, Arachis hypogea)
4. List methods which may be utilized to resolve the four problems associated with ABO
discrepancies.
Discrepancy
Group 1
Group 2
Resolution
 Increase incubation time 15-30 minutes
at room temperature
 Adding one or two drops more of
plasma/serum to the test
 If nor reaction, incubate @4°C for 1530 mins
 Increase incubation time to 30 minutes
@ RT. If no reaction, incubate @4°C
for 15-30 minutes
Group 3
Group 4







Washed RBC 2-3x, cord cells 6-8x
Saline replacement
Microscopic examination
Run antibody screen
Incubate patient’s RBC @37°C for a
short period
Washed with saline @37°C three times
and retype
Resolving the forward type, the
patient’s s can be treated with 0.01 M
dithiothreitol to disperse IgM-related
agglutination
References:
Harmening, D. (2017). Modern Blood Banking and Transfusion Practices (7th ed.). Philadelphia:
F.A. Davis, 1983. Print.