A medical assistant is preparing to administer a PPD test to a patient to screen for tuberculosis. 24-72 hours after injection, the patient returns for an evaluation. Which of the following is the BEST method to assess for a positive reaction?
Assessing the redness of the injection site
Performing venipuncture to analyze blood response
Measuring the diameter of the induration area in millimeters with a ruler
Conducting a capillary blood test