My T will often tell me right before we start that he's stepping out to pee. I used to joke with him that he didn't have to tell me, but he still does. I've only interrupted a sesion to visit the restroom once, and that was more for hiding than a biological reason. However, one week, I was a few minutes early and took use of the facilities before he had finished with his current client. It was an unpleasant experience that I thought I had masked well enough with the provided aerosol air freshener. Apparently not though, as when T made his pre-session visit, I noticed he turned the ventilation fan on when he left. Embarassing.