I have never digged into the matter, but the closest existing thing which resembles your idea is that apparently, in Japan, there are toilets which do automatic

I have never digged into the matter, but the closest existing thing which resembles your idea is that apparently, in Japan, there are toilets which do automatic testing and reporting. That seems like a neat idea because it does not require any kind of invasive procedure, but it is likely also a bit limited in what it can test for.