20 18 introduction of tuberculosis examination methods for immigrants in the United States

Tuberculosis examination is an important item of physical examination before entering the United States, which directly affects whether you can pass the visa. So how to check tuberculosis? Next, let's take a look at the 20 18 introduction of tuberculosis examination methods for American immigrants.

A, tuberculosis skin test (tuberculosis skin test)

After subcutaneous injection of 5 tuberculin units, the results were observed after 48-72 hours. If there was no reaction, it was negative. For high-risk groups, if there is a red mass larger than 5mm, it is considered positive; For people at moderate risk, masses larger than 10mm are regarded as positive; Low-risk people with a mass greater than 15 mm are considered positive. See WebMd instructions.

Second, if the skin test of tuberculosis is positive.

You can arrange a chest X-ray to check whether there are shadows in the lungs. If there is no abnormality, there may be two situations: (a) many people in China have been vaccinated with BCG, and there will be false positive reactions; (two) have been exposed to tuberculosis, but cured by autoantibodies or other reasons, there is no active tuberculosis in the body.

Third, if the chest radiograph is normal.

But if you want to make a further diagnosis of (a) or (b) mentioned above, you can have another blood test, QuantiFERON? -TB gold test, a new test method approved by FDA in 20065438+0, is not interfered by BCG.

You may have noticed that tuberculosis skin test is obviously subjective (including how to define high-risk groups and accurately measure tumor size), and it is interfered by false positives such as BCG, and the accuracy is low. So, can you do chest X-ray directly, or even QuantiFERON TB gold test?

It should be possible (please consult a doctor), but the immigration physical examination includes free TB skin test, while the chest X-ray is charged (35~65 dollars), and you may need to go to the radiology center. QuantiFERON TB gold test is going to the laboratory, which is more expensive (about $350). Therefore, most people still do a free tuberculosis skin test first: everything will be fine if there is no problem; If there is any problem, pay for further inspection.