Fecal occult blood negative

Stool is the body's waste that is excreted through the large intestine. Normally, bowel movements occur once or twice a day. We can diagnose some diseases by observing the frequency and quality of bowel movements. Normally there is no blood in the stool, except during menstruation for women. People may also experience blood in their stool when they have hemorrhoids. So besides these, what other diseases can occult blood in stool be seen in?

Fecal occult blood (also known as fecal occult blood) refers to a small amount of bleeding in the digestive tract, in which the red blood cells are digested and destroyed, there is no abnormal change in the appearance of the stool, and the bleeding cannot be confirmed by the naked eye or under a microscope.

The ferrous heme in hemoglobin has a role similar to that of peroxidase and has weak peroxidase activity. It can catalyze hydrogen peroxide, release new oxygen, and oxidize the colorless receptors into colored substances.

1. o-Toluidine method

Reagents: ① 150g/l o-toluidine-glacial acetic acid solution: weigh 150g of o-toluidine and add glacial acetic acid to 1000ml. Or use 10g/l o-toluidine solution: weigh 1g of o-toluidine, dissolve it in a mixture of 50ml of glacial acetic acid and 50ml of anhydrous ethanol, place it in a brown bottle, and store it in a refrigerator at 4°C. It can be used for 8 to 12 weeks. If it turns dark, it should be re-prepared.

②3% hydrogen peroxide solution.

2. Pyramide hole method

Reagents: ①50g/l pyramide: weigh 5g of pyramide (aminopyrine), add 95% ethanol to 1000ml, and shake until completely dissolved.

② Glacial acetic acid,

③3% hydrogen peroxide solution.

3. Colorless malachite green method

Reagents: ①10g/l colorless malachite green: weigh 1g colorless malachite green and dissolve it in 100ml 95% ethanol, shake until completely dissolved. If it turns green, add a little zinc powder and filter after fading. Add a small amount of zinc particles to the filtrate and store it in a brown bottle.

② Glacial acetic acid solution

③3% hydrogen peroxide solution.

4. Methylaminophenol sulfate method

Reagents: ① 10g/l methylaminophenol sulfate acetic acid solution: weigh 1g of methylaminophenol sulfate, dissolve it in 40ml of distilled water, add 30ml of glacial acetic acid to dissolve, add distilled water to 100ml and mix well. Store in a brown bottle away from light. If there is any discoloration, re-prepare.

②3% hydrogen peroxide solution.

Method: Take a small amount of feces and apply it to the center of the glass slide, add 3 drops of 10g/l aminophenol sulfate acetic acid solution and 3 drops of 3% hydrogen peroxide solution, mix well, and observe the results immediately.

Negative (-): No rose red or cherry red color appears after 3 minutes;

(+): Rose red or cherry red appears within 30 to 60 seconds;

Strong positive (++): Rose red or cherry red appears immediately;

Strongest positive (+++): Immediately turns deep rose red or deep cherry red;

Notes on occult blood test:

1. 3% hydrogen peroxide is easy to lose its effectiveness. Add it on the blood film before use. It can be used only when bubbles are generated.

2. Latent blood meal: Do not eat latent blood meal for three days before the test, that is, limit the consumption of meat, liver, blood, potatoes, taro, radish, etc.

3. It is prohibited to use iron, copper, chlorophyll agents, potassium iodide, bromide and other drugs for post-testing.

4. The test equipment should be heated to destroy the contaminated peroxidase.

5. The specimens should be sent for examination immediately after collection, and stool samples should be collected from the surface and inside of the stool for examination.

Clinical significance of fecal occult blood

1. In the early stage of digestive tract cancer, 20% of patients may have a positive occult blood test. In the late stage, the positive rate of occult blood in patients can reach more than 90%, and it can be persistently positive. Therefore, fecal occult blood test can be used as the preferred indicator for digestive tract tumor screening.

2. The fecal occult blood test of patients with gastrointestinal bleeding and gastrointestinal ulcer is mostly positive or intermittently positive.

3. Diseases that can cause more red blood cells to appear in the stool, such as dysentery, rectal polyps, hemorrhoidal bleeding, etc., can also cause a positive reaction in the occult blood test. Pay attention to further gastrointestinal endoscopic examination for any abnormalities.

Fecal occult blood test

A fecal occult blood test requires the collection of three stool samples. Usually a small stool sample collected with the end of a cotton swab is enough. Stool samples should be collected at different times of the day because colon cancer bleeds sporadically rather than continuously.

You can buy a fecal occult blood test kit (such as the Mayinglong Daan Gene Diagnostic Test Kit) at a pharmacy and do the fecal occult blood test at home, or your doctor can do a fecal occult blood test for you during your appointment.

After the stool sample is collected in a clean container, it can be analyzed by monitoring the color change on the test card or by sending the sample directly to the doctor on duty in a special container and envelope. Your doctor on duty will observe and analyze the sample under a microscope using chemical reagents.

Mayinglong Daan Gene's "Fecal Occult Blood Detection Reagent" can detect hemoglobin in the stool of patients with bloody stools to screen for digestive tract malignancies such as rectal cancer and detect early symptoms of rectal cancer as early as possible. The detection reagent has an effective detection rate of over 87% for early gastrointestinal malignancies related to rectal cancer, and is significantly effective in discovering and preventing early gastrointestinal related diseases.

When symptoms of blood in the stool occur, be vigilant and get tested in time, which can effectively screen for malignant tumors such as rectal cancer and provide appropriate treatment.