Various methods are used to detect the presence of allergens. Skin testing is usually preferable because it is simple and less expensive than serum samples performed in the laboratory. Skin test results are available almost immediately and are more sensitive than the lab (RAST) test. We use the Greer Pick as a testing device. This is a 6 pronged applicator, similar to the TB tine test. A properly applied scratch test will result in some abrasion of the epidermis but will not result in bleeding or scarring. There is some mild discomfort during the actual test, but it doesn’t last long. After the tests are applied, patients should anticipate some itching. These tests can be interpreted within 20 minutes. The assistant will grade the test depending on the size of wheal and redness, in relation to both the positive and negative controls.
Intradermal tests are performed if the scratch tests are negative. This is usually done during the same visit. These tests are performed by injecting approximately .02ml of a specially diluted extract into the most superficial layer of skin, using a needle and syringe specially designed for intradermal allergy testing. Each injection produces a small “bleb” at the injection site. Again you may experience some mild discomfort during the test only. Skin tests will be interpreted within 20 minutes.