Patchtestiä

Patchtestiä, or patch testing, is a common dermatological diagnostic procedure used to identify the specific allergens that are causing a patient's allergic contact dermatitis. This condition manifests as an itchy, red rash that appears after the skin comes into contact with a particular substance. Patch testing helps pinpoint the responsible allergen by recreating a mild, controlled exposure to a range of potential culprits.

The test involves applying small quantities of common allergens, mixed with a petrolatum-based vehicle, to the patient's back. These are then covered with special adhesive patches. The patient is instructed to keep the area dry and avoid vigorous activity that might dislodge the patches. After 48 hours, the patches are removed, and an initial reading of the skin's reaction is performed. A second reading is typically conducted 24 to 72 hours after patch removal, as some allergic reactions may be delayed.

A positive patch test result is indicated by a localized eczematous reaction, such as redness, swelling, itching, and sometimes blistering, at the site of a specific allergen. The intensity of the reaction can help determine the significance of the allergen. A negative result means that the tested substance did not provoke an allergic reaction in the patient. Patch testing is a valuable tool for diagnosing contact allergies, allowing patients to avoid the identified allergens and manage their condition effectively.