Barium swallow

I am only at the "met the crtiteria stage" however, I have been reading what to hope and wait for next..what is the barium swallow and what does this tell them?

 the barium swallow tracks ( I believe) any issues you might have with reflux. The VSG can increase refulx problems or cause them if the tendancy is there. 
The barium helps them to decide if you are therefore a better candidate for RNY