The difference between weak positive and positive

Sometimes when friends go for check-ups, they will find that the results may be small, weakly positive or positive. For such results, friends should go to the doctor in time to review the results. In fact, there is not much difference between a weakly positive test and a positive test, but it depends on what the test item is. For example, if it refers to a fecal occult blood test, as long as it is related to a positive test, it is not good.

Fecal occult blood test is a method for measuring gastrointestinal bleeding, mainly used to detect small amounts of bleeding that are not visible to the naked eye. Also called o-benzidine method (OB). Fecal occult blood testing remains the most widely used and evaluated test in colorectal cancer screening today. The test is quick, simple, and painless.

principle

A Colorectal cancer can develop without any early warning signs. Cancer can grow in the lining of the colon for several years before spreading to other parts of the body. Before any symptoms occur, the proliferating tissue usually oozes a small amount of blood, which is then excreted in the stool. A fecal occult blood test can detect small amounts of blood in the stool. Multiple and persistent positive occult blood tests indicate chronic gastrointestinal bleeding and further examination should be conducted to alert the presence of gastrointestinal tumors.

B The ferrous heme in hemoglobin has an activity similar to that of peroxidase, which can catalyze hydrogen peroxide to release new oxygen, oxidizing the acceptor o-tolidine into o-toluidine, which appears blue. The depth of color reflects the amount of hemoglobin, that is, the amount of bleeding. A highly sensitive tester can detect 0.2~1mg/L of hemoglobin, which is equivalent to 1~5ml of bleeding in the digestive tract.

Reagents

Fecal occult blood test card (can also be made at home)

method

Take a small amount of stool and smear it on the fecal occult blood test paper, then add 3% hydrogen peroxide and observe.

Observations

(-)Does not turn blue within 2 minutes

(+) turns blue after 30~60s

(++) Immediately turns blue-green

(+++) Immediately turns dark green

Precautions

1. The stool specimen should be picked from the center of the stool mass. It should not be mixed with bleeding from the anus or rectum. The stool should be fresh. To increase the chance of detecting blood in the stool, stool samples can be collected multiple times.

2. 3% hydrogen peroxide must be effective. A positive control test should also be done. Apply hydrogen peroxide on the blood smear. If there is foam, it can be used.

3. Do not consume animal blood, meat, liver, iron supplements (ferrous sulfate, ferrous citrate, red supplement pills, ferrous fumarate), or foods rich in chlorophyll (spinach, green vegetables) within 3 days before the test to avoid false positive reactions; do not take large amounts of vitamin C or other reducing substances to avoid false negative reactions.

4. Bleeding gums, nosebleeds and menstrual blood can also lead to a positive reaction.