TB Tests
Skin Tests (TST/TCT)
Pictures & Pages/Related Info
Why do we do the skin test?
To figure out if the person may have TB Germs in the body.
The skin test is not perfect. It can miss TB infection in some people with Active TB. It can also miss TB infection if it has been less than 8 weeks since the bacteria entered the body.
Once a person has a positive skin test, it should never be repeated. The test will always stay positive, even if there is no more TB in the body.
‘Positive’ and ‘Negative’ Test Results
You may hear around the nursing people saying a test is ‘positive’ or ‘negative’. For testing, this wording can be confusing because it doesn’t mean the same as ‘good’ or ‘bad’.
When a person has a ‘positive’ skin test:
You can think about it like a ‘YES’.
A positive skin test = “Yes, there might be TB bacteria in the body”.
The skin test cannot tell the difference between Latent and Active TB. This means that if a person gets a “positive” skin test, they will need more testing to make sure they don’t have Active TB.
What is it?
A nurse will poke the person with a needle on the forearm just below the skin.
A very small amount of liquid (called PPD) will be injected under the skin which forms a bubble.
If the person has or has had TB bacteria in their body, a bump will rise where the injection was. It takes 2 days for the bump to grow (it goes away after a few days).
Getting the results:
The skin test must be read by a nurse 2 or 3 days later.
The nurse will use a ruler to see how big the bump is
In Nunavik, usually a bump of 5mm or bigger is considered ‘positive’ for TB (meaning they DO have or had in the past, TB in their body).
Other Info
After the TB skin test:
A person will be asked to wait 15-minutes in the clinic after their skin test poke to be sure they don’t have an allergic reaction.
You should encourage a person not to scratch or rub at the poke spot.
It’s good to remind a person that they can’t read their skin test themselves.
Redness or a small bump doesn’t necessarily mean they have TB.
No visible redness doesn’t necessarily mean they don’t have TB.
The test can be a hard test to do so sometimes the nurse will have to repeat the test.
Skin test should not be done if the person has had:
A ‘positive’ skin test in the past.
TB in the past.
The skin test can be used in screening for Latent TB.
Example conversation with someone who is being asked to do a skin test:
Reassure
Alright so based on your conversation with the nurse the other day, they would like you to do a skin test. Have you done a skin test before?
The skin test helps the nurses and doctor check if you have TB Germs in your body.
What
During the skin test, the nurse will insert a needle just below the skin and make a little bubble filled with liquid.
There might be a little bit of blood but usually it’s just like any other needle, small as a bug bite.
The test will be done today but then you will need to come back in 2 days, at this time. Can you come back on (DAY) at (TIME)?
After Test
Okay great, you’re almost done. We just need you to wait in the waiting room for 15 minutes to make sure you don’t have an allergic reaction to the needle.
Also, at the spot where they did the skin test, try not to scratch or rub on the spot.
Again, just a reminder, we need to see you in 2 days. Even if there is no redness or no bump, sometimes it’s under the surface so the nurse really has to be the person to look at it.
After the 2 days
Thanks for coming back in. The nurse is just going to take a pen and draw across where they put in the needle to check if you had a reaction