Abo Discrepancies Procedure
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ADVENTIST HEALTHCARE LABORATORY SERVICES SECTION: BLOOD BANK PROCEDURE#lll Title: ABO DISCREPANCIES ABO DISCREPANCIES Principle: A discrepancy exists when the result of red cell tests disagree with that of the serum tests. When a discrepancy is encountered, it must be resolved. The interpretation is delayed until testing and resolution is complete. If the clinical condition of the patient makes it necessary to transfuse before the problem is resolved, only group 0 red cells of the appropriate Rh type may be issued. If the problem cannot be resolved on site, a specimen will be sent to the American Red Cross reference lab for resolution. Procedure: A.
B.
Initial tests 1.
Repeat front and back grouping on the same sample. Reflex/order another ABO test in the LIS and result in the LIS.
2.
Wash the patient and/or reagent red cells several times and re-test.
3.
Incubate tests at room temperature or 4C to facilitate detection of weak antigens or antibodies. An appropriate control (group 0 cells if testing patient cells or autologous cells if testing patient serum) is needed to rule out interference of broadly reactive agglutinins.
Discrepancies due to unexpected serum reactions 1
2.
Cold reactive auto-agglutinins (Anti-I, Anti-H) a.
Warm the serum and reagent red cells to 37C before mixing and testing.
b.
Re-test with cold autoadsorbed serum.
Anti-A, suspected a.
Type the patient with Anti-A1 lectin to demonstrate the cells belong to a non-A1 subgroup.
b.
Test the serum against several examples (preferably three) of A1, A2 and 0 cells. Agglutination must be seen with all A1 cells and
ADVENTIST HEALTHCARE LABORATORY SERVICES SECTION: BLOOD BANK PROCEDURE #1II Title: ABO DISCREPANCIES
3
3.
Treat the patient cells with ficin to increase the reaction with anti-A or anti-B. Enzyme treated 0 cells must be tested in parallel as a control.
4.
Mixed field agglutination may be seen in a patient receiving nonspecific ABO group cells, bone marrow recipients or with fetal/maternal bleeds. The patient's history is essential in these cases.
5.
Subgroups Ax -
does not react with human anti-A but will react 1+ - 2+ with anti-A,B. May react with some monoclonal anti-A.
A3 -
presents a mixed field reaction with anti-A and anti-A,B.
Subgroups of B are less common than subgroups of A. The AABB Technical Manual may be used as a reference in discerning subgroups. 6.
Acquired antigens a.
Acquired B phenotype is characterized by serum with strong antiB and red cells agglutinated strongly by anti-A and weakly by antiB. 1)
2)
b.
If acquired B antigen is suspected, check the patient's diagnosis. It is often associated with carcinoma of the GI tract. Test the patient's serum against autologous red cells. The patient's anti-B will not agglutinate his/her own red cells that carry the acquired B.
Acquired A-like antigens may be seen in a condition known as Tn polyagglutination, in which defective synthesis leaves abnormal antigenic structures on the red cell surface. Group 0 cells that have been Tn-activated behave as if they have an acquired A antigen. Treat cells with ficin to degrade the molecule and eliminate reactivity with anti-A.
Reporting results: 1.
All initial reactions are recorded as seen in the LIS per routine procedures, no interpretation for the ABO group is entered until the discrepancy is resolved.
ADVENTIST HEALTHCARE LABORATORY SERVICES SECTION: BLOOD BANK PROCEDURE#111 Title: ABO DISCREPANCIES
4
2.
Additional testing is recorded on the "ABO Discrepancy Worksheet."
3.
Once resolved, the ABO group is interpreted in the LIS. An exception report will generate because the front and back type disagree with the logic table defined in the LIS. Enter a comment on the exception to explain any additional testing performed.
Notes: The AABB Technical Manual may be used as a reference for other specialized testing related to ABO discrepancies. References: 1. 2.
AABB Technical Manual, 12th edition, 1996. Standards for Blood Banks and Transfusion Services, AABB, 18th edition, 1997.
ABO DISCREPANCY WORKSHEET Patient's Name
Med Record #
Date
Backtype at RT A1 cells
Tech
Backtype at 4C
A2 cells
B cells
Auto
A1 cells
A2 cells
B cells
Auto
Other:
A2 cells
B cells
Auto
Other:
Anti-A,B
Anti-D
Other:
Backtype with 4 drops serum A1 cells
A2 cells
Backtype at 37C
B cells
Auto
A1 cells Other:
Saline replacement backtype A1 cells
A2 cells
B cells
Auto
Other:
Suspected anti-Al (A1 lectin typing of patient is ordered and resulted in LIS) Patient serum with
#1
#2
#3
Al cells A2 cells 0 cells Front type with washed cells Anti-A
Anti-B
Anti-A,B
Anti-D
Front type at room temp 30 min Anti-A
Anti-B
Front type at 4C Anti-A,B
Anti-D
Anti-A
min
Anti-B
Patient 0 cells
ADVENTIST HEALTHCARE LABORATORY SERVICES WASHINGTON ADVENTIST HOSPITAL Takoma Park, Maryland
B.
Initial tests 1.
Repeat front and back grouping on the same sample. Reflex/order another ABO test in the LIS and result in the LIS.
2.
Wash the patient and/or reagent red cells several times and re-test.
3.
Incubate tests at room temperature or 4C to facilitate detection of weak antigens or antibodies. An appropriate control (group 0 cells if testing patient cells or autologous cells if testing patient serum) is needed to rule out interference of broadly reactive agglutinins.
Discrepancies due to unexpected serum reactions 1
2.
Cold reactive auto-agglutinins (Anti-I, Anti-H) a.
Warm the serum and reagent red cells to 37C before mixing and testing.
b.
Re-test with cold autoadsorbed serum.
Anti-A, suspected a.
Type the patient with Anti-A1 lectin to demonstrate the cells belong to a non-A1 subgroup.
b.
Test the serum against several examples (preferably three) of A1, A2 and 0 cells. Agglutination must be seen with all A1 cells and
ADVENTIST HEALTHCARE LABORATORY SERVICES SECTION: BLOOD BANK PROCEDURE #1II Title: ABO DISCREPANCIES
3
3.
Treat the patient cells with ficin to increase the reaction with anti-A or anti-B. Enzyme treated 0 cells must be tested in parallel as a control.
4.
Mixed field agglutination may be seen in a patient receiving nonspecific ABO group cells, bone marrow recipients or with fetal/maternal bleeds. The patient's history is essential in these cases.
5.
Subgroups Ax -
does not react with human anti-A but will react 1+ - 2+ with anti-A,B. May react with some monoclonal anti-A.
A3 -
presents a mixed field reaction with anti-A and anti-A,B.
Subgroups of B are less common than subgroups of A. The AABB Technical Manual may be used as a reference in discerning subgroups. 6.
Acquired antigens a.
Acquired B phenotype is characterized by serum with strong antiB and red cells agglutinated strongly by anti-A and weakly by antiB. 1)
2)
b.
If acquired B antigen is suspected, check the patient's diagnosis. It is often associated with carcinoma of the GI tract. Test the patient's serum against autologous red cells. The patient's anti-B will not agglutinate his/her own red cells that carry the acquired B.
Acquired A-like antigens may be seen in a condition known as Tn polyagglutination, in which defective synthesis leaves abnormal antigenic structures on the red cell surface. Group 0 cells that have been Tn-activated behave as if they have an acquired A antigen. Treat cells with ficin to degrade the molecule and eliminate reactivity with anti-A.
Reporting results: 1.
All initial reactions are recorded as seen in the LIS per routine procedures, no interpretation for the ABO group is entered until the discrepancy is resolved.
ADVENTIST HEALTHCARE LABORATORY SERVICES SECTION: BLOOD BANK PROCEDURE#111 Title: ABO DISCREPANCIES
4
2.
Additional testing is recorded on the "ABO Discrepancy Worksheet."
3.
Once resolved, the ABO group is interpreted in the LIS. An exception report will generate because the front and back type disagree with the logic table defined in the LIS. Enter a comment on the exception to explain any additional testing performed.
Notes: The AABB Technical Manual may be used as a reference for other specialized testing related to ABO discrepancies. References: 1. 2.
AABB Technical Manual, 12th edition, 1996. Standards for Blood Banks and Transfusion Services, AABB, 18th edition, 1997.
ABO DISCREPANCY WORKSHEET Patient's Name
Med Record #
Date
Backtype at RT A1 cells
Tech
Backtype at 4C
A2 cells
B cells
Auto
A1 cells
A2 cells
B cells
Auto
Other:
A2 cells
B cells
Auto
Other:
Anti-A,B
Anti-D
Other:
Backtype with 4 drops serum A1 cells
A2 cells
Backtype at 37C
B cells
Auto
A1 cells Other:
Saline replacement backtype A1 cells
A2 cells
B cells
Auto
Other:
Suspected anti-Al (A1 lectin typing of patient is ordered and resulted in LIS) Patient serum with
#1
#2
#3
Al cells A2 cells 0 cells Front type with washed cells Anti-A
Anti-B
Anti-A,B
Anti-D
Front type at room temp 30 min Anti-A
Anti-B
Front type at 4C Anti-A,B
Anti-D
Anti-A
min
Anti-B
Patient 0 cells
ADVENTIST HEALTHCARE LABORATORY SERVICES WASHINGTON ADVENTIST HOSPITAL Takoma Park, Maryland
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