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Tareq Abadl: Coombs Test Explained in a Simple and Clear Way
Apr 10, 2026, 15:52

Tareq Abadl: Coombs Test Explained in a Simple and Clear Way

Tareq Abadl, Medical Laboratory Specialist and Director of the Blood Bank at Dr. Abdelkader Al-Mutawakkil Hospital, shared a post on LinkedIn:

”Coombs Test
…the blood cell detective!

In our lab, we have a famous detective called the Coombs Test. His main job is to uncover the presence of antibodies attacking red blood cells.

It’s not a simple case, because he has two investigation methods:

Direct Coombs Test
(the detective at the crime scene):

Steps:

  • Take a blood sample from the patient.
  • Wash the red blood cells to remove plasma or free antibodies.
  • Add a reagent called Anti-human globulin.
  • If antibodies or complement are stuck on the surface of red blood cells then Agglutination occurs (clumping of RBCs).

Used in cases like:

  • Autoimmune hemolytic anemia.
  • Transfusion reactions.
  • Hemolytic disease of the newborn.

A positive result means: ‘the crime has already happened’, meaning antibodies are bound to RBCs and destroying them.

Indirect Coombs Test
(the detective among the suspects):

Steps:

  • Take the patient’s serum (plasma).
  • Add reagent red blood cells with known composition.
  • If antibodies are present in the serum, they bind to the added RBCs.
  • Add Anti-human globulin reagent.
  • If agglutination occurs, it means free antibodies are present in the serum.

Commonly used in:

  • Cross-matching before blood transfusion to ensure compatibility.
  • Antenatal screening for mothers to detect antibodies that may affect the fetus.

A positive result means: ‘there are hidden criminal intentions’ meaning antibodies in the serum that could cause future problems.

Key difference:

  • Direct test focuses on crimes that already happened.
  • Indirect test focuses on potential crimes in the future.

Both rely on the same principle:
Using Anti-human globulin reagent to detect antibodies, with results shown as agglutination.”

Tareq Abadl: Coombs Test Explained in a Simple and Clear Way

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