How to Read a Tuberculosis Skin Test

Step-by-Step Guide

1. 1

   Step 1: Go to your doctor for the tuberculosis skin test.

   You will be given an injection of a purified protein derivative into the inner forearm that will result in a 6-10 mm welt that will disappear within a few hours., Do not place a bandage over the site of the test for the required 48 to 72 hours.
   
   You can wash and dry your arm carefully.You also should not scratch or rub the test area on your arm.
   
   This can cause redness or swelling that may cause the results to be misread.
   
   You can apply a cold washcloth on your arm if it is itchy., The test must be read within 48-72 hours.
   
   If you do not come back within 72 hours, the test is considered invalid and will have to be repeated., Use your fingertips to find the induration.
   
   This is a hard, dense, raised formation with definite borders.
   
   If there is a firm bump, use a pen to mark the widest edges of the induration on the forearm.The only part that is important for your test results is the hard bump.
   
   The reddened area or any slight swelling does not count towards the size of the induration.
   
   You cannot always see the induration.
   
   You must find the induration with your fingertips., The test site may be red, but that does not mean you have TB.
   
   You have to measure the induration.
   
   This induration is measured across your forearm in millimeters.Use a ruler with millimeter measurements.
   
   Place the edge of the ruler with "0" on the left edge of the raised bump where you marked it with a pen.
   
   Look where the mark made on the right side of the bump falls on the ruler.If the mark is between two different lines, use the lower measurement. , An induration of 5mm or more is categorized as positive in individuals in the high-risk group.
   
   This group includes people who have:
   HIV received organ transplants been immunosuppressed for various reasons recent contact with a TB positive person chest x-ray consistent with old healed TB end stages of renal (kidney) disease, An induration of 10mm or more is categorized as positive in people in the moderate-risk group.
   
   This includes people who: immigrated recently from a country with widespread TB use injection drugs work in healthcare settings, prisons, nursing homes, or other similar areas have clinical conditions that put them at risk, like diabetes, leukemia, low body weight are children under age 4 are children and adolescents exposed to high-risk adults, For those not in the high or moderate-risk group, an induration of 15mm or more is considered positive.
   
   This includes all individuals, regardless of any risk factors they might have.
   
   The test is also considered positive if there are blisters present, even if there is little swelling., If there is no firm bump, the result is negative.If there is soft swelling or redness, but no noticeable hardened bump that can be felt at the site, it is a negative.Even if you believe your skin test is negative, you must return to the doctor to have it professionally read.
2. 2

   Step 2: Leave your arm uncovered.

3. 3

   Step 3: Return to your doctor.

4. 4

   Step 4: Find and mark the induration.

5. 5

   Step 5: Measure the induration.

6. 6

   Step 6: Determine if the individual is in the high-risk group.

7. 7

   Step 7: Determine if the individual is in the moderate-risk group.

8. 8

   Step 8: Look for a large induration for everyone else.

9. 9

   Step 9: Look for a negative result.

Detailed Guide

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