I have discovered some large hernia's in the patdown process. To make this easier on you though, I would suggest following your doctors advice on the truss and if you get pulled for additional screening due to AIT showing something or the WTMD alarming or something similar, inform the officer right up front that you have a hernia and if you are wearing the support truss for it. You may be required to submit to a private screening so that it can be checked. You are not required to remove it UNDER normal circumstances. I hope that answers your questions.