What happens if I have to get a pee test at the doctor a few weeks after I've taken ecstasy?

I've heard ecstasy stays in your system for like a month? What if someone took some one day then like two weeks later or whatever(before it got out of their system) had to go to the doctor for whatever reason and had to do a pee test? Wouldn't it show up on the papers or whatever? What would happen, can that person get in trouble? What about if they smoked weed and it showed up?

: http://alcoholdrugstreatment.info/what-happens-if-i-have-to-get-a-pee-test-at-the-doctor-a-few-weeks-after-ive-taken-ecstasy