In this situation, the discrepancy can be resolved by washing and re-suspending patient RBCs in saline , followed by repeat forward typing with anti-A and anti-B. Acquired B is a rare event.
What should be the first thing that a medical technologist can do when there is an ABO discrepancy?
- Retest the sample first, using a different method, if available.
- Check for technical or clerical errors.
- Remember that the weakest reactions are usually the ones that are in doubt.
- Complete the antibody screen and note positive reactions.
What causes ABO discrepancy?
Blood group discrepancy develops when the results of red cell typing do not match with plasma typing , or if the previous and present results do not match 3 . ABO discrepancies may be due to clerical errors or technical problems with a sample or during testing.
When do ABO discrepancies occur?
An ABO discrepancy occurs when the results of forward and reverse typing do not match . The reactions shown are described below in descending order: Patient red cells with reagent anti-A: negative reaction. Patient red cells with reagent anti-B: 4+ agglutination.
What are the four ABO discrepancies?
The table that follows provides four useful categories. Weak, missing reactions (including mixed field) in the forward (red cell) typing. Unexpected reactions in the forward (red cell) typing. Weak or missing reactions in the reverse (serum) typing.
What is detected in ABO reverse typing?
The back/reverse type mixes an individual’s plasma with reagent RBCs positive for antigen A, and separate reagent RBCs positive for B antigen. The test also measures visual agglutination or lack of agglutination . Most ABO antibodies are immunoglobulin (Ig) M.
What are common technical errors resulting to ABO discrepancies?
Miscellaneous problems may cause ABO discrepancies, including: Cold reacting autoantibodies that result in spontaneous RBC agglutination or a positive direct antiglobulin test (DAT) Mixed red blood cell populations due to massive transfusion. Unexpected alloantibodies unrelated to ABO antigens.
What is the principle of ABO blood grouping?
Principle: The ABO and Rh blood grouping system is based on agglutination reaction . When red blood cells carrying one or both the antigens are exposed to the corresponding antibodies they interact with each other to form visible agglutination or clumping.
What are the different ABO discrepancies?
Group I – Discrepancies that are associated with unexpected reactions in the reverse grouping. Group II – Discrepancies that are associated with unexpected reactions in the forward grouping. Group III – Discrepancies between forward and reverse grouping caused by protein or plasma abnormalities.
How do you reverse blood typing?
Reverse typing refers to the testing of a patient’s serum for the presence of ABO antibodies . The patient’s serum is mixed with known red cells in a test tube. A specified number of drops of patient serum are placed into each of three properly labeled tubes.
What is forward and reverse typing?
Forward typing- A blood typing procedure whereby patient red blood cells are mixed with Anti-A and Anti-B reagents . ... Reverse typing – A blood typing procedure where patient serum is mixed with reagent A cells and reagent B cells. The results should be the opposite of forward typing.
How do you resolve acquired B?
Patient Results
This ABO discrepancy can be resolved by testing patient plasma with patient red blood cells . Patients who are truly group A, without any true B antigen, will demonstrate a negative auto control.
Does O blood group have H antigens?
If a person has blood group O, the H antigen remains unmodified . Therefore, the H antigen is present in the highest amounts in blood type O and in the least amounts in blood type AB.
What are the causes of Pseudoagglutination?
Pseudoagglutination in blood grouping and cross-matching, may be regarded as a very simple protein test; if it is absent, no inferences can be drawn, but, when it is present, it may be the first clue to the presence of a dysproteinemia, usually caused by a severe, chronic disease, probably cancer or infection .
What is a subgroup in blood bank?
As with other blood group systems, the ABO system has variant phenotypes with a genetic basis. The term “subgroup” refers to phenotypes with variations in the structure or number of the A and B antigens , related to variations in the enzymes that produce them.
What is anti c blood?
Anti-c antibody develops in individuals sensitized through previous exposure and is associated with acute and delayed hemolytic transfusion reactions as well as hemolytic disease of the newborn (HDN). Most antibodies produced against Rh antigens are of the immunoglobulin (Ig) G type.
