Direct Coombs TestDirect Coombs Test

Direct Coombs Test

Direct Coombs Test, The coombs test is used to check your blood for antibodies, that start attacking your red blood cells and cause lysis of red blood cells. The Destruction of red blood cells by these antibodies is termed as Autoimmune hemolytic anemia.


The The Coomb’s test detects agglutination or clumping of red blood cells. The agglutination of the red blood cells during the test indicates a positive result (Antibodies are present against Red blood cells). If no clumps is detected, The test result will be negative it means that test (Antibodies are not Present, It is absent).

What is the other name of Coomb’s Test:

Coombs Test are also called Antiglobulin Test, Direct Coombs Test (DAT)

Direct Coombs Test:


The direct antiglobulin test (DAT) Direct Coomb’s test is performed by adding anti-human globulin to patient RBCs. The direct Coomb’s test is used to check your red blood cells surface for the attachment of antibodies or complement system.

Principle Of Direct Coombs Test:

A positive direct Comb’s test shows you have antibodies attached to your red blood cells surface. This test is done on the newborn’s blood Sample usually in the setting of a newborn with jaundice.

Causes Of Positive Direct Coomb’s Test:

  • Autoimmune hemolytic anemia
  • Systemic Lupus Erythematosus
  • Antiphospholipid Syndrome
  • Acute Lymphocytic Leukemia
  • Erythroblastosis fetalis
  • HIV / AIDS
  • Maleria
  • Infectious Mononucleosis
  • Syphilis
  • Mycoplasma infection
  • Toxicity Due to drug

How To Performed The Test:


  • Firstly Collect the 3 to 5ml blood in EDTA tube.
  • The patient’s RBCS are washed with normal saline.
  • Removing the patient’s own. Serum.
  • Then Centrifuge with antihuman globulin, also known as coombs reagent.
  • After centrifugation if Immunoglobulin or Complements factor have been fixed on to the RBCs surface, the antihuman globulin will agglutinate the RBCs and the direct Comb’s test will be positive.


You can see result easily by using microscope. If the antihuman globulin will agglutinate the RBCs it is called Positive Coombs Test

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