With the attention paid to the understanding of Helicobacter pylori (Hp), many physical examination projects have also added an important content of hp testing.
The blood draw is positive, the blowing is negative, which one should be believed? How can I be sure that my test results are correct?
Today, we will analyze several common detection methods one by one.
I. Breath Test (UBT)
UBT is the most common means of examination, including carbon 13 and carbon 14, the accuracy of the two is basically no difference, both above 95%. It's just that carbon-13 is less radioactive than it is, and it is suitable for children under 12 years of age and lactating and pregnant women. Generally speaking, as long as this test is positive, it is a current infection.
However, this test often appears false negative, possibly because:
1. Within one month, you have taken antibiotics, detoxification and detoxification chinese herbal medicines or proprietary Chinese medicines, and even some health care products; Chinese medicines such as skullcap, skullcap, rhubarb, dandelion and other herbs and proprietary medicines containing these ingredients;
2. Within 14 days, the acid suppressants (that is, xxprazole, xx titerines), bismuth agents (if gum bismuth, licidela, bismuth hypocarbonate, etc.);
3. Disease factors: active bleeding of peptic ulcer, gastric malignancy, severe atrophic gastritis accompanied by diffuse intestinal metaplasia, bile reflux gastritis, due to the reduction of the bacterial load in the patient's stomach, it may lead to false negative test results;
4. Some foods that can temporarily inhibit Hp, such as eating raw garlic.
suggestion:
1. Before doing the breath test, be sure to stop the above related drugs, fasting for more than 4 hours, do not smoke, drink irritating drinks 3 hours before the examination, and do not speak after taking the medicine to ensure the accuracy of the results;
2. If there are the above diseases, if they are negative, it is best to confirm each other in combination with other tests such as other test methods.
Second, Hp antibody detection (serological test)
It is often referred to as a blood test, usually called gastric function three (four) tests, or Helicobacter pylori antibody tests.
It reflects the status of Hp infection over time and is the only test that is not affected by recent medications and local lesions in the stomach.
Because it tests for Hp antibodies, even if it is positive, it can only determine whether it has been infected, not whether it is an infection. That is to say, you have been infected, and after it has been eradicated, you will still appear positive. However, if it is negative, it can be concluded that there is no infection. That said, its negative results are reliable.
note:
1. Qualitative detection of serum antibodies cannot be used for post-treatment review.
2. Serological methods can be used as a diagnostic means for current infection in the case of active bleeding of peptic ulcer, gastric MALT lymphoma, and severe atrophic gastritis accompanied by diffuse intestinal metaplasia, especially when other test methods test results are negative.
3. Rapid urokinase experiment (RUT)
When doing the gastroscopy, the doctor will take out a small piece of gastric mucosal tissue, test it on a special test strip, and the results will be produced quickly. It is the fastest, most convenient and cost-effective method of invasive detection.
But it can also appear false negatives for the following reasons:
1. Due to the uneven density of Hp distribution in the stomach, the material is often not sure that it is exactly taken;
2. The subjective factors of the observer, the observation time, the quality of the reagent, and the humidity and temperature of the experimental environment will affect the results;
3. As with the breath test, it is affected by certain drugs: H2 receptor antagonists, proton pump inhibitors, bismuth agents, antibacterial drugs, gastric acid deficiency and bleeding, which will increase the possibility of false negatives.
If the test is positive, it can be concluded that the present infection is present;
If negative and symptomatic hp infection, other tests are needed.
IV. Stool Hp Antigen Detection (SAT)
It is an easy-to-use, rapid and safe non-invasive test with a sensitivity and specificity of more than 90%, comparable to the carbon-13 urea breath test or the carbon-14 urea breath test, especially for children with poor adherence.
The 2015 consensus recommends SAT as an alternative method for evaluating efficacy after diagnosis and eradication treatment.
Subjects only need to keep stool samples without taking any reagents orally, and are suitable for all ages (including children and the elderly) and all types (including pregnant women) without any toxic reactions.
Because hp antigens are tested, they can accurately reflect hp's present infection, and a positive can be identified as a present infection.
Subjects can leave feces in the morning for Hp antigen testing, and diarrhea stool or overspoiled stool is considered a substandard specimen and cannot be tested. This is one of the main causes of false negatives.
Source: Gastrointestinal disease
Editor: Ren Mileage Reviewer: Xiao Ran