dumping from IBS or post gallbladder

I am in the process of being approved for WLS. I have a past history of dumping/diarrahea. My internest thinks it is from having my gallbladder removed several years ago. I have an Rx that I drink every morning that keeps it under pretty good control. I am concerned that the surgery might make it worse. I don't want to have diarrhea all the time. I asked the surgeon about this on my first consult he didn't seem to think it would be a problem. Anyone out there that had this problem before surgery that can let me know how surgery affected you?