Editing Nursing Skills and Procedures (section)

=== Intradermal ===
Used for tuberculin skin testing and allergy testing. The needle is inserted bevel up at a shallow angle until the bevel is just covered, and a 6 to 10 mm wheal should form. The site is not massaged. A tuberculin test is read at 48 to 72 hours by palpating and measuring induration, not erythema. Interpretation thresholds are 5 mm in the immunosuppressed and close contacts of active cases, 10 mm in higher-risk groups such as recent immigrants, injection drug users, and health care workers, and 15 mm in people with no known risk factors. A positive skin test indicates exposure, not active disease, and is followed by chest imaging and symptom assessment.