Latent Tuberculosis Infection: A Guide for Primary Health Care Providers

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Appendix C

Administration and Measurement of the TST*

Administration

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).

Measurement

• 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.