Occult blood test (OBT):
If there is blood with stool, the result is positive by doing 0ccult blood test. Occult blood test (OBT) is usually performed using two methods.
The methods are:
1. Benzidine method
2. And Toluidine method
At present reporting can be done very easily and accurately with the help of special type of paper strip (ICT Method) made by various reagent companies.
If there is fresh blood in the stool, it can be identified with the naked eye or microscopic examination, but if for some reason the blood changes with the stool which cannot be identified with the naked eye or microscope, then it is possible to diagnose it by doing 0ccult blood test.
Occult blood test: Benzidine method:
- First you need to make Benzidine reagent for this test.
- Benzidine reagent should be prepared by mixing 4gm of benzidine powder with 100 ml glacial acetic acid in a clean container.
- This reagent can be used up to 4 months after making. Now a clear test for the test
- Make a solution by adding stool and clean water to the tube.
- In another test tube, mix 1 ml stool solution and 1ml benzidine reagent together and add a few drops of hydrogen peroxide (H2O2).
Results:
If the color of the mixture changes to blue, then occult blood test: positive
And if there is no change in the color of the mixture, then occult blood test: Occult blood test negative
Occult blood test: Toluidine method:
- First make a solution by mixing some stool and distilled water well in a clean test tube.
- The solution should be filtered and taken to a test tube.
- The solution should be boiled and cooled.
- In another test tube, take four drops of ortho-toluidine and mix it with 1 drop (20 volume) of hydrogen peroxide.
- Now add 1 drop of stool solution to the mixture of ortho-toluidine and hydrogen peroxide and mix.
Results:
If the mixture turns blue, then 0ccult blood test: Positive
And if there is no change in the color of the mixture,
then the occult blood test: Negative
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