No one has told me to worry about damage to the sphincter, but I live in a tiny little town with limited medical access. I do it once a week with an 18mm dilator, stretching what I believe is scar tissue. I don' get leakage, just a lot of gas after doing it. I deal with a cold-rectal surgeon, not a GI doctor, asI have been told the GI guys, except for specialized ones aren't the best source of info or treatment once you have a J-Pouch. What do you think?