Are their any std/sit that cant be detected!! thru blood, urine, or pap smear???

Depends: You must look for STD's using the proper sampling method for each. There are diseases commonly known as STD's that can be found a variety of ways. There are at least a dozen infectious diseases that can pass sexually, but are not labeled as STD's. If you are worried about a specific one or more, be sure to specify that to the doc doing the testing so they can do appropriate studies.