PPD

As I understand it the size of the raised area from the skin test is key, not all of the redness. If there is any doubt they will send you for a chest xray. There is also a gold standard serology test, gamma interferon I think, that can definitively tell if you're positive. If your chest xray comes back negative but the skin and blood tests are positive and you're asymptomatic then you may have latent t.b. which will require a prophylaxis antibiotic to help keep you from converting to active t.b.

The redness/erythema is not indicative of a positive reaction - it's only an induration/raised area, and then only if the induration is >10mm. I always get a big red (flat) splotch, because I've got super sensitive skin that overreacts to anything! If you've had an induration previously and had the chest xray - what did that show? Did it show latent TB (ie: granulomas on lung tissue) or was xray completely clear?

Hi 4boysmama, when I did the chest xray, it was clear so the test was negative. I just hope the big red patch does not get understood as positive because I dont want to go through the hassle of taking xrays. Thanks for your response!!!

If you have ever tested positive you will always test positive. So all you will need to say is I test positive and they will just send you for the X-ray. Happens to my mom because she used to live in England and a vaccine they give there causes her to always have a positive PPD, so they just do the chest X-ray. Good luck. It just means you were exposed, doesn't mean you have an active TB infection, that's why they do the chest x-ray.

I just got mine done last week and it was a huge red blotch. Ended up being negative because the area wasn't raised at all, just a little bruised looking.

You need to discuss with your physician or health department.