bathroom etiquette

When you work in a large office building you don't know everyone by name. I've been working at the same place for 4 years now so lot's of times i'll recognize you by face but not by name. Of course the people in my team i know by name, but not everyone else. So in 4 years, other then the people i sit with all day, i've made acquaintances with the people on the same pee schedule as I. You know the people you bump into on your way in/out of the can. Today, at the sinks, i ran into cute-blonde-girl-with-the-high-piched-voice. And today she is sporting 2 black eyes and a major bruise on her forehead. It took everything i had in me to not blurt out "HOlY FUCK! what the hell happened to your face?" As it did not look anything like the marks of a nose job, nor did i think it very polite to ask weather or not everything is ok at home... what is the proper bathroom etiquette in this situation.... how much concern should be shown to someone who's name you don't know but with whom your bladder obviously has a tight bond.

And how weird is it that this is the second person in the last 5 days that have shown up to work with a black eye.... somethings going on and i haven't been informed.... although come to think of it i guess thats a good thing.