I think that's outside our.... You would have to know more about how the labs work in different countries. In some countries, it would be easy to get a lab that was fully accredited by some kind of international standard.
The other piece of it, if you're worried about identity, is to have the place where the medical tests take place accredited, because of course, there are ways of trying to ensure that people are giving specimens themselves and are not bringing them along. That's something that could be addressed not just through the lab but through the medical centre.