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'''Coombs Test''' also referred to as the Antiglobulin test, is a clinical laboratory assay that helps in identifying antibodies that can attach to the surface of red blood cells (RBCs) or platelets, leading to their destruction. This test plays a critical role in diagnosing certain blood disorders where the patient's immune system erroneously generates antibodies against their own RBCs or platelets. Moreover, it is utilized in the determination of blood type. The Coombs test is a two-part procedure, involving the Direct Coombs test and the Indirect Coombs test.
{{Infobox medical test
| name = Coombs test
| image = Coombs test schematic.png
| caption = Schematic representation of the Coombs test
| purpose = Detects antibodies that act against the surface of red blood cells
}}


== Direct Coombs Test ==
The '''Coombs test''', also known as the '''antiglobulin test''', is a clinical blood test used to detect antibodies that may bind to the surface of red blood cells (RBCs). It is primarily used in the diagnosis of [[hemolytic anemia]], [[hemolytic disease of the newborn]], and in [[blood transfusion]] compatibility testing.


The Direct Coombs Test (Direct Antiglobulin Test, DAT) is employed to detect antibodies that are bound to the surface of red blood cells in the patient's body. A positive result typically indicates conditions such as autoimmune hemolytic anemia (AIHA), in which the body's immune system mistakenly produces antibodies against RBCs, causing hemolysis, or destruction of the red blood cells.<ref name=":1">{{Cite web|url=https://www.ncbi.nlm.nih.gov/books/NBK559201/|title=Coombs Test|date=2020|access-date=2023-05-18}}</ref>
==Types of Coombs Test==
There are two main types of Coombs tests:


== Indirect Coombs Test ==
===Direct Coombs Test===
The '''Direct Coombs Test''' (DCT), also known as the '''Direct Antiglobulin Test''' (DAT), is used to detect antibodies or complement proteins that are bound to the surface of red blood cells. This test is commonly used to diagnose conditions such as autoimmune hemolytic anemia and hemolytic disease of the newborn.


The Indirect Coombs Test (Indirect Antiglobulin Test, IAT) is used to screen a patient's serum for the presence of antibodies against RBCs. If these antibodies are present and are specific to antigens on the recipient's RBCs, they can cause transfusion reactions or Hemolytic Disease of the Newborn (HDN). It is thus an important part of pre-transfusion compatibility testing and prenatal testing of pregnant women.<ref name=":1" />
[[File:Algorithm in positive direct antiglobulin test (DAT, or direct Coombs test).png|thumb|Algorithm in positive direct antiglobulin test]]


== Clinical Significance ==
===Indirect Coombs Test===
The '''Indirect Coombs Test''' (ICT) is used to detect antibodies that are present in the serum and are capable of binding to red blood cells. This test is often used in prenatal testing of pregnant women and in testing blood prior to transfusion.


The Coombs test, both direct and indirect, plays a crucial role in the field of hematology and transfusion medicine. It helps in the diagnosis of autoimmune hemolytic anemia, monitors the condition of patients with chronic lymphocytic leukemia or lymphoma, assists in predicting and managing potential complications in blood transfusion, and provides vital insights into the hemolytic conditions of the newborn.
==Procedure==
The Coombs test involves the following steps:


== Methodology ==
1. '''Sample Collection''': A blood sample is collected from the patient.
2. '''Addition of Coombs Reagent''': The Coombs reagent, which contains anti-human globulin, is added to the blood sample.
3. '''Observation for Agglutination''': The sample is observed for agglutination (clumping) of red blood cells, which indicates a positive result.


The Coombs test involves the use of antiglobulin serum (Coombs reagent) that reacts with the antibodies on the red blood cells. The agglutination or clumping of RBCs indicates a positive test, demonstrating the presence of surface antibodies on the red blood cells.<ref name=":1" />
==Clinical Significance==
{{stub}}
The Coombs test is significant in several clinical scenarios:
[[Category:Health]]
 
[[Category:Medicine]]
* '''Autoimmune Hemolytic Anemia''': The direct Coombs test can confirm the presence of antibodies that are causing the destruction of red blood cells.
[[Category:Hematology]]
* '''Hemolytic Disease of the Newborn''': The test can detect antibodies in the mother that may attack the red blood cells of the fetus.
[[Category:Medical Tests]]
* '''Blood Transfusion''': The indirect Coombs test is used to screen for antibodies in the recipient's serum that may react with donor red blood cells.
 
==Limitations==
While the Coombs test is a valuable diagnostic tool, it has limitations. False positives can occur due to non-specific binding, and false negatives may occur if the antibody levels are too low to detect.
 
==Also see==
* [[Hemolytic anemia]]
* [[Blood transfusion]]
* [[Hemolytic disease of the newborn]]
* [[Autoimmune disease]]
 
{{Medical tests}}
[[Category:Blood tests]]
[[Category:Immunology]]
[[Category:Immunology]]
{{stub}}

Latest revision as of 02:47, 11 December 2024

Coombs test
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Purpose Detects antibodies that act against the surface of red blood cells
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The Coombs test, also known as the antiglobulin test, is a clinical blood test used to detect antibodies that may bind to the surface of red blood cells (RBCs). It is primarily used in the diagnosis of hemolytic anemia, hemolytic disease of the newborn, and in blood transfusion compatibility testing.

Types of Coombs Test[edit]

There are two main types of Coombs tests:

Direct Coombs Test[edit]

The Direct Coombs Test (DCT), also known as the Direct Antiglobulin Test (DAT), is used to detect antibodies or complement proteins that are bound to the surface of red blood cells. This test is commonly used to diagnose conditions such as autoimmune hemolytic anemia and hemolytic disease of the newborn.

Algorithm in positive direct antiglobulin test

Indirect Coombs Test[edit]

The Indirect Coombs Test (ICT) is used to detect antibodies that are present in the serum and are capable of binding to red blood cells. This test is often used in prenatal testing of pregnant women and in testing blood prior to transfusion.

Procedure[edit]

The Coombs test involves the following steps:

1. Sample Collection: A blood sample is collected from the patient. 2. Addition of Coombs Reagent: The Coombs reagent, which contains anti-human globulin, is added to the blood sample. 3. Observation for Agglutination: The sample is observed for agglutination (clumping) of red blood cells, which indicates a positive result.

Clinical Significance[edit]

The Coombs test is significant in several clinical scenarios:

  • Autoimmune Hemolytic Anemia: The direct Coombs test can confirm the presence of antibodies that are causing the destruction of red blood cells.
  • Hemolytic Disease of the Newborn: The test can detect antibodies in the mother that may attack the red blood cells of the fetus.
  • Blood Transfusion: The indirect Coombs test is used to screen for antibodies in the recipient's serum that may react with donor red blood cells.

Limitations[edit]

While the Coombs test is a valuable diagnostic tool, it has limitations. False positives can occur due to non-specific binding, and false negatives may occur if the antibody levels are too low to detect.

Also see[edit]



Medical tests
Blood tests
Imaging
Cardiac tests
Urine tests
Stool tests
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