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Coombs Test - Indirect

400
4.4
NABL, ISO
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Overview
Interpretations
FAQ's
Coombs Test - Indirect

Overview of Coombs Test - Indirect

What is Coombs Test - Indirect?

The Indirect Coombs Test, also called Indirect Antiglobulin Test (IAT) is a laboratory procedure performed to identify the presence or absence of antibodies in blood directed against antigens found on red blood cells to determine compatibility for blood transfusion, Rh incompatibility between pregnant woman and her child, and the possibility of hemolytic anemia occurring due to autoimmune disorder.

Sample Type

The sample type collected for Coombs Test - Indirect is: Blood

Preparation for Coombs Test - Indirect

  • No special preparation required

Why Get Tested for Coombs Test - Indirect?

The Indirect Coombs Test is performed:

·    When donating blood, tissue, organ, or bone marrow or while getting registered as a potential donor

·  Before receiving a blood transfusion or blood components transfusion to determine compatibility with donated blood

·    Before pregnancy and during pregnancy to determine the risk of incompatibility between the mother and fetus

·    To determine if hemolytic anemia is caused due to an autoimmune disorder



Understand more about Coombs Test - Indirect

The red blood cells have specific antigen markers present on their surface. These marker antigens are glycoproteins and help the body to recognize its own type of Red Blood Cells (RBCs). Antibodies are naturally produced against incompatible RBC antigens when there is exposure to incompatible red blood cells. Three commonest antigen markers found on RBCs are A, B, and Rh, and the presence or absence of these antigen markers is used to determine the blood group of a person.

Blood transfusion between incompatible blood types causes an antigen-antibody reaction which causes the RBCs to clump together (agglutination) and this results in their destruction. Hence blood groups of donor and recipient must match to ensure the success of the blood transfusion or organ transplant. Agglutination may also occur due to Rh incompatibility between Rh-negative pregnant woman (who is having Rh antibodies because of previous sensitization) and her Rh-positive child which may cause antibodies in the mother to cross the placenta and attack the RBCs of the foetus. In some autoimmune disorders, antibodies are produced against antigens on the body’s own RBCs. These antibodies may attack the ‘self’ RBCs and cause agglutination.

The Indirect Coombs Test is performed on the principle of the antigen-antibody reaction between incompatible blood groups. The collected blood specimen is treated with a large range of collected or synthetic human RBC antigens and observed under a microscope. If agglutination (clumping) of RBCs is seen upon treatment with a particular antigen, antibodies against that antigen are already present in the blood specimen. Antibodies against RBC antigens A and B occur naturally, while antibodies against other RBC antigens are produced upon exposure to the corresponding antigen. A similar test called the Direct Coombs Test is performed to detect the presence of antibodies (bound to RBCs) against the body’s own RBCs (autoimmune antibodies) that may be the cause of autoimmune hemolytic anemia.


What Results of Coombs Test - Indirect mean?

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 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.


Patient Concerns about Coombs Test - Indirect

Frequently Asked Questions about Coombs Test - Indirect

Q. How is this test performed?
This test is performed on a blood sample. A syringe with a fine needle attached is used to withdraw blood sample from a blood vessel in your arm generally from the inner side of the elbow area. The doctor, nurse or the phlebotomist will tie an elastic band around your arm which will help the blood vessels to swell with blood and hence makes it easier to withdraw blood. You may be asked to tightly clench your fist. Once the veins are clearly visible, the area is cleaned with an antiseptic solution and then the needle is inserted into the blood vessel to collect the sample. You may feel a tiny pinprick during the procedure. Blood sample once collected is then sent to the laboratory.
Q. Is there any risk associated with this test?
There is no risk associated with the test. However, as this test involves a needle prick to withdraw the blood sample, rarely, a patient may experience increased bleeding, hematoma (blood collection under the skin) formation, bruising or infection at the site of needle prick.
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Provided By

NABL

ISO

Trident Diagnostics - A unit of Trident Diagnostics & Healthcare Pvt. Ltd. is a holistic healthcare centre built on the tenets of accuracy, accessibility and affordability, a vision that has enabled quality healthcare convenience to everyone. Our omnibus service includes laboratory and diagnostic testing, subject expert consultation and a fully equipped pharmacy. Our dynamic team of highly qualified clinical trial professionals cater to routine as well as critical diagnostic services, discharging professional responsibilities with highest sense of integrity.\r\nStrategically located in West Bengaluru, Trident Diagnostics is spread over a sprawling area of 5000 sqft, divided categorically into 3 floors. Our fully automated and bar coded laboratory boosts of state-of-the-art infrastructure equipped with cutting edge technologically precise lab and diagnostic equipment and practices. Our core focus areas include but not limited to clinical pathology, hematology, hormones and histopathology with imaging services in Radiology, Cardiology and Gynecology to name a few. We operate hub and spoke model for sample collection and our collection centres are fanned out across the city with many Lab-to-Lab tie-ups. We have a team of dedicated riders and phlebotomists and are capable of outstation sample collection with reporting. We also provide home sample collection for our customers with a simple booking procedure over the phone. We manage round-the-clock laboratory at Sri Rama Multi Specialty Hospital and Trauma Centre in Sunkadakatte and have tie up with leading insurance aggregators. The entire team at Trident Diagnostics work towards the sole motto \Sarve Janah Sukhino Bhavanthu\. We are dedicated to all the ethical and moral standards of Lab technology that help our doctors and patients to get accurate and precise reports at the minimum turnaround-time at a right value.

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