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Dr. Surabhi Srivastava

BDS

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Dr. Ashish Ranjan

MBBS, MD (Pharmacology)

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Coombs Test - Indirect

Also known as Indirect antiglobulin test

₹479

You need to provide

Blood

This test is for

Male, Female

Test Preparation

Duly Filled Coombs (Direct/Indirect) Form is mandatory.

Understanding Coombs Test - Indirect

What is Coombs Test - Indirect?

The Coombs Test - Indirect is a blood test that is used to detect IgG antibodies against red blood cells (RBCs). It is often done during prenatal testing of pregnant women and before a blood transfusion. It assists in identifying blood compatibility problems that could lead to complications like hemolytic disease of the newborn (HDN), transfusion reactions etc., or diagnose autoimmune hemolytic anemia and monitor individuals with autoimmune disorders.

The Coombs Test - Indirect, also known as the indirect antiglobulin test (IAT), looks for antibodies in the blood that may react with RBCs, causing immune-related complications. It helps identify antibodies that are freely floating in the bloodstream, which can potentially bind to RBCs.

The indirect Coombs test is used to screen for blood type compatibility, especially during pregnancy to detect IgG antibodies that are likely to pass on into the fetal blood via placenta leading to hemolytic disease of the newborn(HDN). It checks for Rh incompatibility between the mother and the fetus. Also, it is done in crossmatch screening for blood transfusion to prevent immune reactions and if someone has a blood disorder to identify any harmful antibodies that could be present.

The Coombs Test - Indirect helps identify antibodies early which supports safe blood transfusion practices between the donor and the recipient and pregnancy management, safeguarding both the mother and the baby.

No special preparation is required for this test. However, a duly Filled Coombs (Direct/Indirect) Form is mandatory. Inform your doctor about all the medications or supplements that you may be taking as these could affect the test results, potentially requiring dosage adjustments or temporary discontinuation before the test.

Lab test results may vary across laboratories. Interpretation of the test results requires professional expertise. Therefore, do not self-medicate and always consult your doctor to understand your test results correctly. Narrate your complete medical history to help doctors relate your clinical and laboratory findings.

What is Coombs Test - Indirect used for?

The Coombs Test - Indirect is done:

To screen for antibodies that may cause hemolytic reactions during blood transfusions.
To diagnose autoimmune hemolytic anemia.
To evaluate Rh incompatibility in pregnancy.
To determine the cause of anemia, jaundice or hemolysis.
To monitor individuals with a history of hemolytic disease, autoimmune disorders (e.g.,lupus etc.).

What does Coombs Test - Indirect measure?

The Coombs Test - Indirect measures the presence of antibodies in a person's serum that can react with specific antigens on red blood cells. These antibodies are proteins produced by the immune system in response to perceived threats, such as foreign blood group antigens or altered self-antigens in autoimmune conditions. A positive test result suggests the presence of potentially incompatible antibodies, prompting doctors to conduct careful blood type matching before any transfusion.

Furthermore, this test is vital in diagnosing autoimmune hemolytic anemia, where the immune system mistakenly targets the body’s own red blood cells. By revealing the presence of autoantibodies, the Coombs Indirect Test aids in formulating appropriate treatment plans. Overall, the test is essential not only for ensuring safe blood transfusions but also for managing various conditions related to antibody-mediated red blood cell destruction, thus safeguarding individuals' health.

Interpreting Coombs Test - Indirect results

Interpretations

Agglutination: Positive result, antibodies present

No agglutination: Negative result, antibodies absent

Result	Interpretation
Negative	No antibodies detected
Equivocal	Positive in undiluted serum up to 1:16 titre
Positive	Positive in titre of 1:32 or above Positive in increasing titre in subsequent tests

Antibodies are produced in the blood upon exposure to incompatible antigens as during a blood transfusion. Antibodies produced in the first incompatible transfusion produce severe reactions upon subsequent transfusions of the same blood type.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Coombs Test - Indirect

Frequently Asked Questions about Coombs Test - Indirect

Q. What is the purpose of the Coombs Test - Indirect?

The Coombs Test - Indirect is primarily used to detect antibodies in a person's serum that could react with red blood cells, assessing the risk of hemolytic transfusion reactions and diagnosing autoimmune hemolytic anemia.

Q. When is the Coombs Test - Indirect recommended and who should take it?

This test may be recommended if you have symptoms of autoimmune haemolytic anemia such as fatigue, pale skin, and shortness of breath; history of haemolytic disease of the newborn or a positive antibody screen during pregnancy; or in case of unexplained anemia or jaundice or family history of hemolytic anemia.

Q. How is the test performed?

The test involves mixing a sample of the patient’s serum with red blood cells that have known antigens. If antibodies are present, they will bind to the red blood cells, which can then be detected through additional reagents.

Q. Are there any risks or side effects associated with the test?

The Coombs Test - Indirect is minimally invasive and involves only a blood draw. Generally, there are no significant risks, but as with any blood test, some individuals may experience mild discomfort or bruising at the site of the needle.

Q. What is the difference between Direct and Indirect Coombs Tests?

The Direct Coombs test is done to detect the presence of antibodies that are directed against one's own RBCs that occur in cases of autoimmune diseases. The Indirect Coombs test helps to detect the presence of RBC antibodies that are external. The antibodies detected by the Direct Coombs test are present on the surface of RBCs while the antibodies detected by the Indirect Coombs test are found in the serum.

Q. Can the Indirect Coombs Test be used during pregnancy?

Yes, this test is commonly used during pregnancy to screen for antibodies in the mother’s blood that might affect the fetus, especially in cases of Rh incompatibility.

Q. What is the importance of blood compatibility testing?

Blood compatibility testing is crucial to ensure that the recipient’s immune system will not attack the transfused blood, which can lead to serious complications.

Q. What does a positive test result mean?

A positive result indicates the presence of antibodies that could lead to hemolytic reactions, suggesting the need for careful blood type matching before transfusion or further investigation of autoimmune conditions.

Q. What does a negative test result indicate?

A negative result suggests that no significant antibodies are present in the serum, indicating a lower risk of transfusion reactions and typically supporting safe blood transfusion practices.

Q. How often is this test used?

The Coombs Test - Indirect is frequently used in transfusion medicine, particularly for patients with complex blood type histories, as well as in obstetric care to prevent Rh incompatibility in pregnant women.

Q. How does Tata 1mg ensure accurate lab test results?

Tata 1mg ensures accurate lab test results through certified laboratories that use advanced technology and adhere to stringent quality control measures. This commitment to high standards guarantees reliable results.

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