Doctor insights on:
Positive Tb Test Look Like
Skin test: If you had a PPD skin test and you have no risk factors, a positive test is when after 48 to 72 hoursyou have swelling in the site and redness that measures more than 15 mm, it is considered a positive tb. Test.
Mycobacterium tuberculosis is an infectious organism that spreads by droplets coughed out by an infected person. Infection is established initially in lungs, but can spread within lungs & to other body parts, or can become latent, with reactivation occurring years to decades later. With effective treatment, it can be completely eliminated although drug resistant ...Read more
What is important: Is what it feels like - not how it looks. Induration is palpated & measured. Treatment (such as INH) is determined once it is established where this is latent or active TB and the type.
TB Tests: I bet you could google image that question. A positive reaction is read after 48 hours from the test. It would be a raised redness greater than 5 mm in circumference.
Positive PPD test: A positive TB test should look like hard, raised bump with size >5to15 mm depending of the risk category you are in. It should be read in between 48 to72 hours. It is the hardness and not redness which is read. Thanks.
Doc: Either your blood test igra is negative or your skin testing does not show any "bump". This should always be checked by a professional since even health care workers report false results. Best to check with a doc and not pa or np or nurse.
See below: A positive PPD is determined by the presence of swelling (induration) around the injection site. Little or no swelling indicates a negative test. Reddness is not used to determine a neg or pos test.
Chest X ray: It is possible to have active TB with very little symptoms especially early on. However, it is more than likely that you carry the germ for TB in a dormant form, this is called latent tb. No symptoms are expected with latent tb.
If there is a bump: When TB infects the body the infection gets walled off by antibodies. The medical person injects a manufactured antibody under your skin that reacts to the TB antibody. If a bump appears at the injection site after 48 hours it means you have the antibody to TB already in your body and therefore have TB infection. It does not mean that you have active disease or are contagious.
48-72 hours: Tb test is meant to be interpreted in 48-72 hours after being administered on the forearm. Make sure that the induration (not redness) is measured in that time frame & results documented by a health care provider. Further testing may be determined based on your results from the TB test.
Size of induration: After the TB test, the skin at the site can develop swelling (induration). The size of this swelling (measured in millimeters by a health care provider within 48-72 hours) determines whether you have a positive result or not. It is important to not measure the area of redness but the actual size of the swelling around the test site. The cut off value for positive test is based on yr risk factors.
Yes: The TB test can become positive within the first day in someone that has been exposed to TB in the recent past.
Latent vs active TB: If you have a + PPD then you will be screened to determine if you have TB infection or TB disease. The physician will obtain a medical history, physical examination, chest x-ray, & any other pertinent lab tests.
PPD: It is not about hardness of the induration it is about the size of the area of induration. It is harder than surrounding skin.
Infection with Tb: When someone is infected with tuberculosis (TB) germs, the body develops a protective response against them. The TB skin test is a test of the body's response to tb, not the germs themselves. One can have an active infection where they are coughing out TB germs and are a risk to spread tb. Or the body may have had the infection long ago and controlled it so there is no risk now of spread.See 1 more doctor answer
If I tested negative from a TB test and had been around someone who tested positive am I at risk of contracting tb?
TB risk: Yes, the PPD test is not 100%. You might want to get it repeated a month later to see if it is booster positive. Of course it is also possible that you didn't catch it. Many doctors are around people with TB a lot and never catch it.
Yes, I think so.: It may not be an absolute certainty, but I would advise the physician of the fact that there was a primary complex diagnosed and treated (assuming it was) either before the TB test or at the time of results if they are positive. I have never had positive results, but I was told that I had a primary complex - I always tell them the history just to be informationally complete. Best!
Tb test site bled right after injection. Can this give a false positive? Obviously, it was not intradermal. Don't answer if you don't know how to.
Check with your doc: The test was not appropriately administered. You want to ask your doc for a new one. Or get the igra blood test which is better anyway. The skin test is almost in the museum of history of medicine.
Usually unknown: The reasons for false positive PPD are unknown. There is speculation that it could sometimes result from past infections with various TB-like bacteria. Such infections aren't very common, but they are equally frequent in the Netherlands as anywhere else. As long as the tested person is outwardly healthy and definitely does not have tuberculosis, this is nothing to worry about.
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