Sometimes it takes a while for the barium to get into all those nooks and crannies. Most of the time, you'll be moving on one side or another so you probably won't notice that it takes so long. We all know what that means. That's not to say you won't feel uncomfortable. As I mentioned, you'll feel like a balloon and also feel like you just have to get to the bathroom.
Some patients feel cramps when the barium goes in.
If this happens to you, just tell the doctor and he'll slow the flow of the barium until the cramps subside. They have to study the pictures carefully before they can render a verdict. The report is usually dictated the same day so your physician should be able to call the radiologist that afternoon for the report. Glad you asked. There is actually quite a lot you need to do to get ready.