If I take ms contin on a regular basis for pain management and I take an oxycontin on Saturday night, will it show up the same on Monday afternoon in my urine screen. It's a 12 panel test my PM dr does.

That is an interesting question and probably depends on the test. MS Contin is a pure opiate so tests as morphine (which it is). Oxycodone contains only a minute amount of natural opiate undetectable on a standard opiate screen and is otherwise synthetic. Oxycodone can be detected by the presence of the metabolite oxymorphone (not a metabolite of morphine) only if they use that panel. If they are simply using a lower sensitivity setting for morphine (another alternative) then the two would be indistinguishable.

So the two can show up separately or not. Probably PM physicians use the Oxycodone panel.