I girl friend of mine had to have a CT scan the other day. She said they make you drink a litre of water in the hour before it, then you have to stay still during the scan. She said she was dying to pee during the scan.
Was sat next to a slim girl wearing jeans, early twenties the other night in the cinema and after a while it looked like she needed to pee. The odd squirm but mostly her tummy was making sudden jerky movements. Sure enough she went to the ladies after, love that she held it!