A skin biopsy will also be performed. If you are taking anticoagulants (blood thinners), you may be asked to stop taking them for several days, before the procedure, due to the risk of bleeding. For the skin punch biopsy, the skin is numbed with lidocaine and cleaned with betadine and an alcohol swab. Once the skin is anesthetized (numb), a small amount of skin will be collected using a sterile 3 mm punch tool (knife). After removal of the skin, the area where you were tested will be wiped with a sterile gauze, and antibiotic ointment will be applied. Then, it will be covered with a band aid. You will be given a small supply of antibiotic ointment and band aids. You will be asked to clean the skin with soap and water twice each day and to apply the ointment and band aid.