Gall stones: ultrasound before and after to see the change in the contents of their gall bladder?

I was at the hospital yesterday with my wife. She was having severe stomach acid issues. One of the things they checked out was her gall bladder. They did an ultrasound to inspect her gall bladder. They found no visible gall stones. It got me thinking. It seems that there is no scientific evidence that the lumps that we inspect in our excrement after a flush are gall stones. The best I have heard is "I feel so much better after a flush that they must be stones". Has anyone ever been given an ultrasound before and after to see the change in the contents of their gall bladder? This would be an interesting experiment.