Podcast
Questions and Answers
Who first described the Coombs test?
Who first described the Coombs test?
- Dr. Albert Coombs
- Dr. Futoon Al-Rawashde
- Dr. James Watson
- Dr. Robin Coombs (correct)
What does the Direct Antiglobulin Test (DAT) detect?
What does the Direct Antiglobulin Test (DAT) detect?
- Presence of hemoglobin in plasma
- In vitro sensitization of RBC
- Scavenging of free antibodies in serum
- In vivo sensitization of RBC with IgG or complement (correct)
What role do Coombs Control Cells (CCC) serve in antiglobulin testing?
What role do Coombs Control Cells (CCC) serve in antiglobulin testing?
- They provide a quality control measure for antiglobulin tests. (correct)
- They act as a neutralizing agent for unbound globulins.
- They increase the concentration of AHG reagents.
- They facilitate the washing of red cells.
Which molecule does the Antiglobulin Test (AHG) primarily react with?
Which molecule does the Antiglobulin Test (AHG) primarily react with?
What can cause a false-negative result in the antiglobulin test?
What can cause a false-negative result in the antiglobulin test?
What is required for antibody detection in antiglobulin tests?
What is required for antibody detection in antiglobulin tests?
How can IgG-sensitized cells affect antiglobulin tests?
How can IgG-sensitized cells affect antiglobulin tests?
What is the significance of removing unbound proteins before adding AHG serum?
What is the significance of removing unbound proteins before adding AHG serum?
What does a positive DAT result indicate?
What does a positive DAT result indicate?
Which condition is NOT investigated using the DAT test?
Which condition is NOT investigated using the DAT test?
What is the main purpose of the Indirect Antiglobulin Test (IAT)?
What is the main purpose of the Indirect Antiglobulin Test (IAT)?
What should be done first in the DAT procedure?
What should be done first in the DAT procedure?
Which antibody type is primarily associated with hemolytic disease of fetus and newborn (HDFN)?
Which antibody type is primarily associated with hemolytic disease of fetus and newborn (HDFN)?
Which option describes an indirect effect of transfusion on DAT?
Which option describes an indirect effect of transfusion on DAT?
What condition is linked to drug-induced hemolysis?
What condition is linked to drug-induced hemolysis?
What happens to the RBCs if no agglutination is observed in the DAT?
What happens to the RBCs if no agglutination is observed in the DAT?
What does the Indirect Coombs Test (IAT) primarily detect?
What does the Indirect Coombs Test (IAT) primarily detect?
What is the first step in the indirect Coombs procedure?
What is the first step in the indirect Coombs procedure?
What does agglutination indicate in the Indirect Coombs Test?
What does agglutination indicate in the Indirect Coombs Test?
What should be done if no agglutination occurs after the saline phase?
What should be done if no agglutination occurs after the saline phase?
What action is performed after adding AHG in the final step?
What action is performed after adding AHG in the final step?
What does a negative result mean in the Indirect Coombs Test?
What does a negative result mean in the Indirect Coombs Test?
Under what circumstance is a negative result considered invalid?
Under what circumstance is a negative result considered invalid?
During the saline phase of the indirect Coombs test, what is the centrifuge speed?
During the saline phase of the indirect Coombs test, what is the centrifuge speed?
Study Notes
Coombs (Antiglobulin) Tests Overview
- Developed by Robin Coombs in 1945.
- Consists of two main tests: Direct Coomb’s Test (DAT) and Indirect Coomb’s Test (IAT).
Principles of the Antiglobulin Test
- Antibody molecules are globulins; animals produce antibodies against injected human globulins.
- Adsorbed animal serum reacts specifically with human globulins, termed AHG serum.
- AHG interacts with bound human antibodies and complement on red blood cells, enhancing antigen-antibody reactions.
- Unbound globulins can neutralize AHG, potentially causing false-negative results.
Coombs Control Cells (CCC)
- CCCs, or IgG-coated cells, serve as a quality control measure in antiglobulin tests.
- Reactivity with CCC confirms that AHG was added and functional.
- Lack of reactivity indicates the need to repeat the test due to potential neutralization of AHG.
Direct Antiglobulin Test (DAT)
- Detects in vivo sensitization of red blood cells by IgG or complement antibodies.
- Involves washing patient’s red cells, mixing with AHG, then centrifuging to observe agglutination.
- Report results as:
- Positive: Agglutination observed.
- Negative: No agglutination observed.
Indications for DAT
- Used for diagnosing:
- Hemolytic disease of the fetus and newborn (HDFN) due to alloantibodies.
- Hemolytic transfusion reactions.
- Autoimmune Hemolytic Anemia (AIHA) caused by autoantibodies.
- Drug-induced hemolysis related to autoantibodies.
Indirect Antiglobulin Test (IAT) / Group-Screen and Hold (GSH)
- Identifies in-vitro reactions between red cells and antibodies that sensitize.
- Agglutination after AHG addition confirms binding to specific red cell antigens.
- Applications include antibody detection, identification, crossmatching, and weak D identification.
Indirect Coombs Procedure
- Consists of several phases:
- Saline phase (Immediate Spin, IS).
- Incubation phase (37°C).
- AHG phase.
- Involves mixing patient serum with screening cells, incubating, and observing for agglutination.
Interpretation of Antiglobulin Tests
- IAT results:
- Positive test indicated by agglutination after incubation or upon AHG addition.
- Negative results seen when no agglutination is noted, and CCCs are agglutinated.
- If CCCs are not agglutinated, the negative result is invalid and requires re-testing.
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Description
Explore the fundamental concepts of Coombs tests including Direct Antiglobulin Test (DAT) and Indirect Antiglobulin Test (IAT). This quiz delves into the principles behind these essential procedures in blood banking and transfusion science as first described by Robin Coombs in 1945.
