How do they perform Tuberculosis Testing???
What kind of needle do they use?? Some people say they use a normal needle and some say it is like a little pricker. How do they test you for Tuberculosis?
Infectious Diseases - 7 Answers
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1 :
It's called a Mantoux TB test. They inject TB antigens (perfectly harmless) just under the surface of the skin and if you've had an infection before you will have a reaction to the antigen. This is because your body will already have the TB antibodies stored up from prior infection so they respond to the antigen. This causes extreme swelling in the testing area. As for the needle, it's very small and barely hurts at all. I get this tests every 3 months since I work in a laboratory neighboring a TB facility. They're really not all that bad. Hope that answers your question!
2 :
The TB skin test is done with a very tiny needle. It is intradermal test. The medication is placed right under the skin and the area is watched to see if in 72 hours a reaction ( red, raised patch) develops. If you are allergic to the TB skin test you may have a chest X-ray done instead.
3 :
T.B. test could be done by using any kind of needle. usuall they use a 4our headed pricker!!! don't worry it won't hurt at all. they have to put some dead T.B. under your skin to see if your body reacts to it. if it swells up after a day or two, that means your body was exposed to T.B. sometime during your life. If you are old and from 3rd world country, the chances are you were vaccinated for T.B. and that is why you test positive.
4 :
I've had it. The needle is pretty tiny. It's not like a regular shot but you can obviously still feel it
5 :
They use a very small needle, like the needles that diabetics use to give themselves insulin injections. They prick your forearm with the needle & inject the TB solution just under the skin to create a small bump. They give your body 48-72 hours ot react to it. If the bump goes away, then you have not been exposed. If the bump gets larger, you have at sometime been exposed, but this does not mean you have TB, so stay calm. You will from then on, need a chest X-ray instead of the test to be sure you do not have TB. RN
6 :
For a skin test, the normal way is with PPD (purified protein derivative). A very small amount of the fluid is injected just under the skin of the forearm with a tiny, thin needle. If you react to it, the area will become hard and raised. Redness alone doesn't mean a reaction is present. The other way - becoming very common - is a serum test. Your blood is drawn and a QuantiFERON test is done. This test is often done for healthcare workers, and those who work in housekeeping and food service in hospitals and nursing homes. The tine test, done with the little pricker, isn't very accurate so it isn't used much anymore.
7 :
There is the scratch test but by far the more commonly used is the Mantoux skin test which uses PPD (purified protein derivative). Many people mistakenly refer to the test as a "PPD". The usual needle size is 25g 5/8, which is 25 gauge, a small diameter, and 5/8 of an inch long, which is very short. Insulin needles come in a variety of gauges from 25 to 31. Tuberculin needles generally come in 25-27g and the needle is fixed to the syringe. You will have to define the word "normal" when referring to needles as all needles are normal to me. The protein is given as an intradermal injection on the inside of the left forearm. This is just below the surface of the skin and if done skillfully, will be painless. Even when not done skillfully, the sensation is a brief and minor pricking. What you usually (but not always) see afterward is what we call a "bleb", a small bubble created by the protein derivative. You'd be instructed to avoid wiping, rubbing and scratching the bleb. You'd also be instructed to return in 72 hours for a reading. Some places of employement require the two part Mantoux for high-risk folks in which the testing is perormed once and repeated in one week. Readings can be done from 48 to 72 hours but ideally it should be done as close to 72 hours as possible. If for some reason a person cannot return in 3 days, the site can be read in 48 hours. After 72 hours, the results are unreliable. The injection site may become red (this is called erythema). This is not a positive reaction. The injection site may swell (this is called induration). This isn't necessarily a positive reaction. The redness and induration, if there is any, will be measured. 0-4mm is insignificant and is a - result. 5-9mm is + in certain high-risk groups. 10-14mm is + in certain groups with preexisting conditions. 15 or greater is + in any group and any patient. A positive reaction does not indicate active TB but may indicate a previous exposure to the mycobacterium that causes it. You would, in this case, have a chest X-ray and possibly a sputum culture. The sputum culture has the final word. It's also called a sputum AFB, which stands for acid-fast bacilli, a reference to the bacterium and a culture that is postive indicates active TB. Once you have a positive Mantoux, you'll always have one and therefore you will not need to retested this way in the future. Instead, you would have a chest X-ray. If ever you were requested to have TB testing, you would want to speak up and make it clear that you must have a chest X-ray. The QuantiFERON-TB, or QFT, that was mentioned may be an alternative for some. It requires a blood draw but only one office visit instead of two. In this test your blood would be mixed with TB antigens and the interferon-gamma, produced in response to the mycobacterium antigen, would be measured to indicate positve or negative for TB. There are a few disadvantages to this testing. One is that it's reliability to differentiate between TB infection and TB disease hasn't been fully evaluated. Further diangostics would be required
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