Positive TB reaction after 12 hours?

Question

After ruling out a bunch of things, my doctor decided to test me for TB today. The nurse did the test and kinda hit a blood vessel, making the whole thing look look a blood blister rather than a normal blister. It was the size of a pencil eraser.

Now, 12hrs later, the bruised area has flattened out some, but it is encircled with slightly raised redness about the size of a penny.

Is it possible to have a positive reactive result so quickly? or must the test be allowed to run for the full 48hrs before being interpreted? Thanks!

Answer 1

First, there should have been no way to hit a vessel if the injection was appropriately applied. You see, the Mantoux test for TB is an intradermal injection. That means that the contents of the syringe are placed within the layers of skin, just below the surface. This causes what is known as a wheal to form (almost like a blister, just a little deeper). If the nurse did this right, there are no blood vessels (only capillaries) involved to make a bloody mess as you describe.



Also, applying the injection is an insult to your skin. It will be red and raised due to natural inflammation. That is why we wait 48-72 hours to read these tests.



Finally, assuming the test is positive, this is not indicative of an active, raging case of TB. This can only be confirmed via Chest X-ray. A positive Mantoux means that you have been exposed. If you test positive, you will need a chest X-ray. If this film comes back negative, you will need to report to your local health department for a 9-12 month course of antibiotics. This is to prevent a manifestation of the disease should you encounter a comprimise of your immunity or for when you become old.



Good Luck

Answer 2

You're probably seeing the effects of the blood blister still, I have had a few TB tests for work (every 6 months) and they always look a little funky like you're saying for a day or so afterwards.

Answer 3

Mine got to be about four inches in diameter after only a few hours. They decided to go ahead and do chest x-rays because of my reaction combined with my grandmother recently testing positive. My test results were negative they concluded. I just have sensitive skin.