A TB skin test detects whether you have the bacteria that cause tuberculosis. A nurse injects a tiny bit of fluid into your arm skin and two or three days later, the doctor or provider reads this reaction. A TB skin test may appear as one of the requirements among schools, companies, or housing or immigration forms. Washington Medical Clinic, LLC in Silver Spring, Maryland, besides carrying our TB skin testing services offers the explanation of the results written in very simple language.
What is a TB skin test?
The TB skin test is another name often used for the tuberculin skin test or the Mantoux test. However, one thing to be absolutely sure about is that it does not help doctors know if you are unwell today. The test can be considered as a kind of record showing your immune system has been exposed to TB bacilli previously.
A good number of individuals who harbor the TB bacilli in their bodies do not feel sick and are non-contagious. This condition is known as latent TB. Some TB carriers, on the other hand, develop active symptoms and become contagious, and they can spread tuberculosis via air. TB exposure skin testing is the preliminary procedure to find out whether you are a latent TB carrier or a TB-symptomatic patient.
How the TB skin test works
The test takes two visits.
First visit
A skin test for tuberculin involves a small amount of the tubercle bacillus being introduced under the skin of the inner forearm by means of a delicate needle, after the area has been cleansed. The site may appear as a tiny, pale raised bump after the shot. After a few hours or so the bump disappears. It is usually over in a second and the sensation a majority of patients describe is more of a tingling than a true poke.
Second visit
Return in about the time period of 48-72 hours. A skilled medical provider will be looking at your arm and will be measuring any hard, raised area there with a ruler. Only the solid swelling counts. Redness by itself does not.
Ideally, you don’t come within a few days or the doctor’s decision not to repeat the test could still be done. So, you’d need to go under and take the test again if you came after the time limit was passed. In other words, you are to make sure that the spot dries and stays clean. You are not to scratch it, or bandage it, or put a cream on it.
Who should get a TB skin test?
One of the possible ways to detect TB is that your provider may suggest a TB skin test.
- You’re working in health care, schools, child care, or a shelter
- You were born in or resided in a country where TB is prevalent
- You have had close contact with a person who is diagnosed with the TB infection
- You suffer from HIV or another immune system weakening illness
- You’re on medications that will weaken the immune system
- Your job, school, or program will require you to have a negative result
The TB skin test can be done even in infants, children, and pregnant women. Let your doctor know if you have ever experienced a very serious allergic reaction to a skin test.
Positive vs negative TB skin test
How big the firm bump is, determines the test result. What is considered positive varies from your health and how risky it is for you
- For people with HIV, recent close contacts of someone with TB disease, organ transplant recipients, and any person having chest x-ray findings that show scar of old/ previous TB a 5-milli-metre or more bump is indicative of positive result.
- A 10-millimetre or greater firm bump is a positive result for those who very recently have moved from areas where TB is very much common, hospital workers, those persons who are drug injectors and children below 4 years of age
- Everyone else should be diagnosed with a positive TB result when there is at least15 millimeter bump.
Positive TB skin test
If you’ve gotten a positive TB skin test, it indicates that TB bacteria are actually within your body. However, this doesn’t definitely mean that you have active TB disease. To find out more, your doctor will probably order a chest ray and may even get sputum (from your lungs) to test. Latent TB infection is what they might find from their result. This kind of infection usually doesn’t present much of a problem to the affected person, yet it still is a good candidate for medication to prevent it turning into the active phase.
You had better keep a note of a written copy of a positive TB skin test result. The chances are higher than you may think that the same person after being cured could actually show positive in some other subsequent test.
Negative TB skin test
A negative TB skin test means you most probably did not get infected by TB. Your doctor can, however, still ask for TB testing even though the results of skin test are negative but in case the patients have signs and symptoms such as a chronic cough or other TB symptoms (fever, night sweat, weight loss) and have been recently in contact with a TB case. TB is also a disease that can give a “false-negative” or no signs for a few weeks so it might be the reason for a negative TB skin test.
When a TB skin test can be wrong
Testing doesn’t guarantee results. For instance, some with a TB skin test positive reaction may be vaccines who received the BCG vaccine (which is widespread in many countries outside the USA). Additionally, some with impaired immunity test negative to carry the bacteria
A TB blood test will be appropriate in such cases because the result is BCG vaccine-free. Naturally, the best choice is left to your healthcare provider after evaluating your medical history and other information
In other instances, certain jobs are requiring employees to be tested for TB in two steps. The second TB skin test is administered 1 to 3 weeks after the first one. This helps to distinguish between old and recent infections
TB skin test near me: care at Washington Medical Clinic in Silver Spring
If you’re looking for a TB skin test near me, you probably want a place that is convenient and clearly states what the process will be. Washington Medical Clinic, LLC is a comprehensive family healthcare provider located at 10230 New Hampshire Avenue, Suite 340, Silver Spring, Maryland 20903. With us, you can see the board-certified providers or nurse practitioners who handle TB screening and treatment all in one building.
In general, here’s what the process will involve:
- A short visit to get the TB skin reaction
- Second check 2-3 days later to see the result
- Clear explanation of what the result positive or negative means for you
- Recommendations for further exams and therapy if the result is positive
- Documentation required for work, school, or any other purposes
We believe in treating every person as members of our family. Bring your list of medications and records from previous TB tests. Please call (301) 908-2116 or (301) 750-8000 to speak to our office hours and also to plan about insurance coverage.
FAQs
The test is read 48 to 72 hours after the injection. You must return in that window.
No. It means TB bacteria are in your body. A chest x-ray and other tests show whether the disease is active.
Yes. The BCG vaccine and some other mycobacteria can cause a positive TB skin test. A TB blood test can confirm the result.
Not always. A recent infection or a weak immune system can cause a negative result in someone who carries TB bacteria. Your provider may repeat the test or order another one.
Yes, you can wash it gently with soap and water. Avoid scratching, rubbing, or covering the spot until it is read.
