skin scratch test

The skin scratch test is a commonly used physical examination method in dermatology for the examination of allergic skin diseases such as urticaria, drug eruption, atopic dermatitis and the like. Basic Information Specialist Category: Skin Examination Category: Other Inspections Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Normal value: no Above normal: negative: Normal person is negative. Positive: People with urticaria, atopic dermatitis, drugs and food allergies may be positive. Tips: Mainly for diet, avoid spicy foods such as hot and sour foods and high-protein foods such as fish and eggs. It is best to avoid contact or use strong irritating chemicals in daily life. Normal value If you suspect that the skin is allergic to an allergen, you need to do a specific skin scratch test, usually after disinfecting the outer or upper skin of the upper arm, using a needle tip to mark a trace of 05 to 1 cm on the skin to avoid bleeding. For the degree, drop the test substance onto it and wipe it gently. At the same time, when using a variety of allergens, the scratches should have a distance of 4 to 5 cm. The results should be observed 20 minutes after the test, and the test materials should be wiped clean. The reaction standards are as follows: Normal person is negative (-). ±, suspicious, edematous erythema or wheal diameter less than 0.5 cm (cm). +, weakly positive, the wind group has a red halo, the diameter is equal to 0.5 cm. ++, positive, wind blush is obvious, diameter is O.5 ~ 1.0 cm, no pseudopod. +++, strong positive, the wind group has significant redness and pseudopod, diameter greater than 1 cm. Clinical significance People with urticaria, atopic dermatitis, drugs and food allergies may be positive. Note that in highly sensitive subjects, the reaction may occur very quickly. If present, the test substance should be removed and washed immediately to prevent systemic reactions. Abnormal results: edematous erythema, wheal has significant redness and pseudopod. People who need to be examined: patients with allergic skin diseases such as urticaria, drug eruption, and atopic dermatitis. Positive results may be diseases: small spine moss, hot urticaria, recurrent herpes, air conditioning disease, psoriasis, hair disk tumor, wind itching, port wine stains, pediatric drug allergy, pruritic purpura matters needing attention Taboo before the inspection: Mainly diet attention, avoid spicy food such as hot and sour wine and high-protein food such as fish and eggs. It is best to avoid contact or use strong irritating chemicals in daily life. Requirements for inspection: Actively cooperate with the doctor. Inspection process The practice of skin scratch test is to use the blunt instrument to bend the forearm flexor skin, and after 1 to 2 minutes, a wheal is generated at the blunt device, which is positive for the skin scratch. If you suspect that the skin is allergic to an allergen, you can also do a specific skin scratch test by selecting the outer side of the arm or the back skin. After disinfecting the skin, use a needle tip to draw a 0.5 to 1 cm long streak on the skin. No bleeding is used, the test object is dropped on it, and it is lightly rubbed. At the same time, when testing with a variety of allergens, there should be a distance of 4 to 5 cm between the scratches. There must be a control during the test, usually the results are observed 20 minutes after the test, and the test object is wiped off. Patients with positive skin scratch test often twitched in the tight belt, strap, garter, etc., and the wind group produced more due to scratching. It is generally believed that skin scratching occurs due to the involvement of IgE antibodies and is associated with some functional abnormalities in skin mast cells. Not suitable for the crowd Patients with skin scratches. Adverse reactions and risks May cause redness and swelling of the skin.