This image depicts the hands of a clinician, that were in the process of correctly placing a Mantoux tuberculin skin test in this recipient’s forearm, which will cause a 6mm to10mm wheal, i.e., a raised area of skin surface, to form at the injection site. The Mantoux tuberculin skin test is used to evaluate people for latent tuberculosis (TB) infection. In the United States, this skin test consists of an intradermal injection of exactly one tenth of a milliliter (mL) of tuberculin, which contains 5 tuberculin units. Correct placement of this intradermal injection involves inserting the needle bevel slowly at a 5° to 15° angle. The needle bevel is advanced through the epidermis, the superficial layer of skin, approximately 3mm so that the entire bevel is covered and lies just under the skin surface. A tense, pale wheal that is 6mm to 10mm in diameter appears over the needle bevel.