Just another idea. I'm a bangle cuff girl and like mixing it up and don't really want to wear identifying jewellery ! At best this happens once a year for me and my solution is just to pause and in doing so I can remember or identify the arm ; just a faint sense that is still some tension in my armpit although surgery there two years ago. I was asked to identify which breast was affected and I don't have it on automatic so I just had to check it out. I guess there might be an emergency situation where they need to access an arm but I'll take my chances!