Can you get wrong results from pee

If you go get checked out , is it possible to get wrong results from pee, I’ve never heard or experienced going to the doctor (urgent care) and them telling me to pee in a cup & my pee will tell them everything they need to know , normally I get a Pap smear , is it possible for the results to come back inaccurate ? & by inaccurate I mean saying I have something I don’t ?? From just pee

I thought I had a yeast infection & they said I had an std

I was on my period , so when I wiped with the lil wet wipe they gave it didn’t do the job and I had to set the cup down on this little shelf in the bathroom to clean myself up