Like some earlier posters, I suffer from Crohns. Have done since I was seven, so I don't remember ever having had a normal shite - you know, a nice log, then the satisfied "that'll dae for a week" feeling (as described by others).
When I was sixteen my internal plumbing was, ahem, altered shall we say, due to my intestine being completely fucked. For the few days before my op I had NO control over my arse - it was like sulphuric acid dripping out of me, with no warning at all.
When I came round after my op, the surgeon said that my arse muscles were literally paper thin. I'm not fucking surprised.