During a Tuberculin Skin Test (TST), a healthcare
provider administers a small amount of purified protein derivative (PPD)
tuberculin solution beneath the skin, usually on the forearm. This painless
injection is done using a very fine needle. The site of injection is then
marked and left undisturbed for 48 to 72 hours. After this waiting period, a
healthcare professional will examine the test site to measure any raised bump
or swelling that may have developed, providing insight into potential
tuberculosis infection.