What is the procedure for ordering a Mantoux (tuberculin) skin test?

From the Guidelines

To order a Mantoux tuberculin skin test, a healthcare provider should submit a laboratory requisition specifying "PPD skin test" or "tuberculin skin test" through their facility's ordering system, with the test requiring 0.1 mL of purified protein derivative (PPD) containing 5 tuberculin units to be injected intradermally on the inner forearm by a trained healthcare professional, as recommended by the American Thoracic Society and the Centers for Disease Control and Prevention 1.

Procedure for Ordering a Mantoux Skin Test

The procedure involves the following steps:

• The test is administered by injecting 0.1 mL of 5-TU PPD intradermally into the volar or dorsal surface of the forearm, with the forearm being the preferred site 1.
• The injection should be made using a one-quarter- to one-half-inch, 27-gauge needle and a tuberculin syringe, with the needle bevel upward or downward 1.
• A discrete, pale elevation of the skin (a wheal) 6 to 10 mm in diameter should be produced when the injection is done correctly 1.
• Tests should be read between 48 and 72 hours after injection, when the induration is maximum, and the transverse diameter of induration should be recorded in millimeters 1.

Interpretation of Results

The interpretation of results varies by risk factors, with:

• ≥5mm considered positive for immunocompromised or close TB contacts 1.
• ≥10mm considered positive for those with risk factors, such as recent immigrants from high-prevalence countries and injection drug users 1.
• ≥15mm considered positive for low-risk individuals 1.

Patient Advice

Patients should be advised:

• Not to cover the site with bandages 1.
• To avoid scratching the site 1.
• That normal bathing is permitted 1.
• That false negatives can occur in immunocompromised patients, recent TB infection, or very young or elderly patients, and that interferon-gamma release assays (IGRAs) may be a better alternative for these high-risk groups 1.

From the FDA Drug Label

The preferred site of the test is the volar aspect of the forearm. Avoid areas on the skin that are red or swollen. Avoid visible veins Clean the skin site with a suitable germicide and allow the site to dry prior to injection of the antigen. Administer the test dose (0. 1 mL) of TUBERSOL with a 1 mL syringe calibrated in tenths and fitted with a short, one-quarter to one-half inch, 26 or 27 gauge needle.

To order a Mantoux skin test, follow these steps:

• Identify a suitable site on the volar aspect of the forearm, avoiding areas that are red, swollen, or have visible veins.
• Clean the skin site with a suitable germicide and allow it to dry.
• Administer the test dose (0.1 mL) of tuberculin using a 1 mL syringe with a short needle (26 or 27 gauge).
• Ensure the test is performed by a trained health professional and read 48 to 72 hours after administration 2.

From the Research

Procedure for Ordering a Mantoux Skin Test

To order a Mantoux (tuberculin) skin test, the following steps should be considered:

• The Mantoux skin test is the currently accepted standard for determination of infection with Mycobacterium tuberculosis 3.
• Placement and interpretation of the tuberculin skin test should be provided by health practitioners who are qualified as a result of education and experience 3.
• The test should always produce a "wheal" when administered, and if a significant amount of the dose leaks from the injection site or the injection is administered subcutaneously, the test should be repeated immediately at another site 3.

Key Considerations

• Induration, not erythema, should be considered in interpreting the TB skin test 3.
• A history of BCG vaccination is not a contraindication to PPD skin testing 3, 4.
• The larger the reaction to PPD, the greater the probability of TB infection 3.
• Alternative methods, such as dissolving microneedle-array patches, have been explored for tuberculin skin testing, which may offer advantages in terms of ease of use and reduced discomfort 5.

Measurement and Interpretation

• The induration resulting from the TB skin test can be measured using either the palpation method or the ball-point pen technique 4, 6.
• An induration of 10 mm or greater is considered significant 4.
• For individuals with an initial induration of 5 to 9 mm, a two-step procedure is recommended to eliminate the confusion caused by the booster phenomenon 4.