Latent Tuberculosis Infection: A Guide for Primary Health Care Providers
Administration and Measurement of the TST*
The Mantoux test is the recommended TST. It is administered by injecting 0.1 ml of 5 TU of purified protein derivative (PPD) solution intradermally into the volar surface of the forearm using a 27-gauge needle with a tuberculin syringe.
- Obtain results of all previous TST. Ask patient to describe what the test area looked like 2–3 days after administration. Written documentation must be obtained for history to be applicable.
- Avoid areas of skin with veins, rashes, or excess hair.
- Cleanse the area with alcohol swab, allow area to dry, and inject all antigen just below the surface of the skin on the volar surface of the forearm, forming a 6–10 mm wheal (a pale, raised area with distinct edges; has orange-peel appearance and does not disappear immediately).
- If no wheal forms, or if a wheal forms that is less than 6 mm of induration, the test should be repeated immediately, approximately 2 inches from original site or on the other arm.
- If minor bleeding occurs, dab the injection site with a cotton swab.
- Avoid covering the area with a bandage or applying pressure to the injection site.
- Record the date, time, and location of TST administration.
- Instruct patient not to scratch the site, but to use cool compress to relieve any itching or swelling.
- Inform patient of the importance of returning for a reading of the TST within 48–72 hours (2–3 days).
- Give written appointment card for TST reading.
- Provide written information about TST (pamphlet or brochure).
- Measure the induration (hard bump) rather than erythema.
- Palpate area with fingertips, measuring the diameter of induration perpendicular to the long axis of the arm.
- Use ballpoint pen to mark edges of induration.
- Use a tuberculin skin testing ruler or ruler with millimeters to measure the distance between the 2 points.
Recording and Documentation
- Record date TST was administered.
- Record the brand name of the PPD solution, lot number, manufacturer, and expiration date on the patient record.
- Record results in millimeters of induration (0 mm if there is no induration) rather than as positive or negative.
- Record date and time of reading and name of person reading TST.
- Provide written documentation to patient and ordering health care provider.
Storage and Handling
- PPD solution must be kept refrigerated at 36°– 46° F.
- Avoid fluctuations in temperature; do not store on the refrigerator door.
- Syringes must be filled immediately prior to administration.
- Store and transport the tuberculin in the dark as much as possible; avoid exposure to light.
- Tuberculin testing solution should not be stored with other vials, such as Tdap, that could be mistaken for PPD.
* Contact the local health department TB program for training on the Mantoux tuberculin skin test.