Question: Colleagues and I have been having an intense discussion on whether a tuberculosis (TB) test would count as an injection on the MDS. Would I code a TB test as such? Utah Subscriber Answer: Yes, code a purified protein derivative (PPD) test for tuberculosis on the MDS in Section N, according to an example in the RAI Manual, page N-2. For Item N0300 (Injections), you would consider a TB test an injection if it happened within the lookback period of 7 days. Remember to monitor the injection site for localized or systemic reactions.