Understanding a Negative PPD Test: What It Means & Next Steps

A PPD -- purified protein derivative -- test is a skin test for tuberculosis, also known as the Mantoux test or tuberculin skin test (TST). A tiny amount of the protein derivative is injected just under the skin to form a welt, usually on an inner forearm. The injection site is widely circled with ink or a permanent marker to show the injection site's general area and then the test is "read" 48 to 72 hours later. A negative response to the test is the lack of any swelling or induration at the site.

Instructions

• 1

  Wash and glove hands.

• 2

  Position the patient's arm in adequate light to observe the injection site. If the site was not circled at the time of injection, confirm with the patient where the welt was placed.

• 3

  Visually inspect the injection site carefully for any redness, irritation, rash or induration.

• 4

  Run your index finger gently over the injection site to assess for swelling or induration.

• 5

  Note negative PPD test, "- PPD reading" or "neg PPD," in the patient's chart or medical record.