reading a tb skin test

test is positive only if there is an area of induration (hardened lump under the skin) greater than 10mm (some say 15mm). redness doesn't indicate anything.

stidget is right...no induration...negative PPD.

Good teaching on the Mantoux test here:

http://www.vdh.state.va.us/epi/tb/CDCTSTGd.pdf#search='read%20mantoux'

Interesting pic here about what to measure:

http://www.kcom.edu/faculty/chamberlain/Website/lectures/lecture/image/mantouxyn.jpg

Hope that helps!

Good teaching on the Mantoux test here:

http://www.vdh.state.va.us/epi/tb/CDCTSTGd.pdf#search='read%20mantoux'

Interesting pic here about what to measure:

http://www.kcom.edu/faculty/chamberlain/Website/lectures/lecture/image/mantouxyn.jpg

Hope that helps!

Thanks for everyones response. I have definitely come to the conclusion that next time a MD asks me to read his test I will respectfully decline. :) I measured it and since he had a chest xray done the same day as his PPD, he is definitely covered. Again, Thank you to all who responded to my question.

test is positive only if there is an area of induration (hardened lump under the skin) greater than 10mm (some say 15mm). redness doesn't indicate anything.

Per CDC, greater than 5mm induration if you are a healthcare worker or immunocompromised.

Tina, MSN,APRN-BC

Occupational Health Nurse Practitioner

I am confused about TB readings. Does the induration have to be a visible lump under the skin, or under? I have felt tests with no visible lump on top of the skin, but there has been a small amount of hardness beneath.

If there was no induration, or an upraised area of skin (not under), it was most likely a local reaction to the tuberculin. If I see redness, I usually run my finger over the area. If it's completely flat, it's negative. If there is a lump underneath the skin, it's still most likely a local reaction of inflammation. Hope this helps!

Just a question...is anyone (RN) able to read a TB test? My roommate has a friend that needs her read by Monday and was wondering if I could do it. I've never read one before but know we were taught to in school...I just wasn't sure.

In my facility you have to have special training to administer and read TB tests. Without it you cannot place or read the tests. I'm not sure if that's standard though.