Stool occult blood test procedure step by step in lab

Learn about “Stool occult blood test procedure step by step in lab”.

Gastrointestinal bleeding can occur for various reasons and may not always be evident. Hidden blood in the feces, also known as occult blood, can be an indicator of this type of bleeding.

To detect the presence of occult blood, a medical diagnostic test called the Stool Occult Blood Test is used. In this article, you will learn about the principle, procedure, and steps involved in performing an Occult Blood Test.

Principle of Stool Occult Blood Test

The Occult Blood Test works by detecting the presence of heme, the iron-containing component of hemoglobin, in the feces.

Hemoglobin is the protein that carries oxygen in the blood, and when bleeding occurs in the gastrointestinal tract, it can cause small amounts of hemoglobin to be excreted in the feces. The Occult test uses a special chemical reagent to react with heme, resulting in a color change that indicates the presence of occult blood.

Stool Occult Blood Test procedure step by step in the lab

Here are the steps involved in performing an Occult Blood Test:

  • Obtain a Stool Sample: The patient is typically provided with a special collection kit, which includes a small brush or stick to obtain a sample of feces.
  • Apply the Sample to the Test Card: The collected sample is then transferred to the test card, following the manufacturer’s instructions.
  • Wait for the Results: The test card is then left to incubate for a specified amount of time, typically 5 to 10 minutes.
  • Read the Results: After the incubation period, the test card is checked for the presence of a color change, which indicates the presence of hidden blood in the feces.
  • Interpret the Results: If the test is positive, it indicates the presence of hidden blood in the feces and the patient may require further diagnostic testing. If the test is negative, it suggests that there is no hidden blood in the feces and no further testing is required.

NOTE: It’s important to follow the instructions carefully and avoid eating certain foods, such as red meat, that can interfere with the test results, before performing the FOBT.


The Stool Occult Blood Test (FOBT) is a simple, non-invasive medical diagnostic test that can detect the presence of hidden (occult) blood in the feces. By following the procedure steps outlined above, it’s possible to accurately determine the presence or absence of occult blood.

What is a stool occult blood test?

The stool occult blood test is a diagnostic test that checks for the presence of hidden (occult) blood in a stool sample.

How is the occult test performed?

The test is performed by collecting a small sample of stool and placing it on a test strip or into a container that contains the chemical reagent. The test strip or container is then evaluated for the presence of blood.

Is the test painful?

No, the test is not painful. Collecting a small sample of stool is the only required procedure, and this is not painful.

How often should the test be performed?

The frequency of the test depends on individual circumstances like abdominal pain, GIT bleeding and the reason for testing.

What are the possible results of the test?

A positive result indicates the presence of blood in the stool, while a negative result means that no blood was found. The results of the test can be used to diagnose conditions such as colorectal cancer or digestive tract bleeding.

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