in USA we say: to children: "have you gone to the bathroom?" / "Did you go potty ?" / "Did you go pee-pee" (ages 2-5) parent to parent: Did they go to the bathroom? other adults: "GO TO THE BATHROOM" formal and informal informal/idiomatic for adults only (american): "go take a piss" "take a dump" "take a shit" *Note: "Go to the bathroom" is what we mainly say in any case.

Except for speaking to very small children, we don't ask about the specifics of what happens in the bathroom. We just ask, "Did you go to the bathroom?" or say, "I need to use the bathroom." We only ask small children in case they need help to clean the bum after going poop.