Detection method of occult blood test

Traditional methods: reduced phenolphthalein method, benzidine method, o-toluidine method, colorless malachite green method, guaiacol method and pyramide hole method.

2. A brand-new method: tetramethylbenzidine method (household fecal occult blood test paper)-accurate, rapid and effective identification of whether human feces contain occult blood.

Introduction to methodology

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Principle: Heme in hemoglobin has peroxidase activity, which can catalyze hydrogen peroxide, release new ecological oxygen, oxidize receptor reagents and develop color.

Advantages: the results are quick and clear, and can be semi-quantitative.

Disadvantages: A. Poor specificity, greatly influenced by diet. Food and drugs containing ferrous ions interfered with the results, and the false positive rate was 30%. Before occult blood test, instruct patients to avoid iron, animal blood, liver, lean meat and a large number of green leafy vegetables for 3 days. If there is gum bleeding, don't swallow saliva with blood, in case of false positive stool occult blood test.

B. low sensitivity and bleeding volume >; It can detect 90μg/ml.

C. There are many restrictions: patients have a long preparation time in advance. Due to different parts of materials, different reaction times and different judgments on color development, errors will also occur in the same experimental method.

2. A brand-new method-tetramethylbenzidine method (household fecal occult blood test paper)

Principle: The test paper is coated with a layer of tetramethylbenzidine chromogenic dye and peroxide film. In toilets or urinals, hemoglobin and heme in feces can diffuse into the surrounding water. Heme in hemoglobin has peroxidase-like activity, which can release oxygen through peroxide membrane and oxidize colorless tetramethylbenzidine into colored benzidine blue, showing a blue-green appearance.

Advantages: A. No need to collect and treat feces, avoiding bacterial infection, healthier and safer.

B, no special preparation is needed, and the test paper can be directly put into the toilet or urinal, which is simple and easy.

C, the detection process only takes a few minutes, and the detection can be carried out at any time, saving time and cost.

D, 2 minutes can quickly get the test results, high sensitivity (0.2ug/ml, even a small amount of bleeding can be detected).

E. no dietary restrictions, avoid false positives.

F, there is no need for multi-point sampling, which solves the problem of irregular sample collection and avoids false negative (avoiding missed diagnosis).

G the simplest method to detect occult blood in stool in the world; The only FDA-certified fecal occult blood detection technology in China; China SFDA (US Food and Drug Administration) approved the only fecal occult blood test product that is really suitable for home use.

Method summary

A brand-new method-tetramethylbenzidine (household fecal occult blood test paper) is the safest and most convenient for screening early digestive tract malignant tumors. No contact with feces is an important improvement of this method. Compared with the traditional chemical method, it is more scientific, which can effectively avoid the irregularity of multi-point sampling and avoid missed diagnosis. The improved new method is more sensitive, especially suitable for family self-examination of the subjects, which can effectively improve the detection rate of early digestive tract malignant tumors and reduce the mortality rate.