When you are in the middle of a 1-on-1 conversation at a networking event and you need to use the restroom, what is the proper way to excuse yourself?

If you need to excuse yourself from a conversation, I think it is best to say you need to wash your hands and that you will be back in a few minutes. They don’t need to know your going use the restroom too. You can say something like you need to wash my hands as I just arrived; however, I would recommend gong to the restroom before you enter the event!