Hey Mary
Don't believe I've welcomed you to the forum... so here's a belated welcome. As for your question.... here's the scoop on the poop (as far as I'm concerned).. Basically anything that restricts your tract, esp. the colon, rectum or anus, CAN affect the size of stool. One of the methods I use (but then again, everyone knows I'm crazy) for judging how things are going up inside me (apart from pains, cramps, energy levels, appetite, etc.) is the size N shape of my stool. I developed a scale... 1 (being watery diarhea) - to 10, (the best, biggest, healthiest looking stool you ever had).. and I pretty much use it each N every trip to the bathroom to give me a handle on how I'm doing. I found that you can't judge by just this.. but if use in conjunction with how you are doing overall, its a pretty acurate indicator of where your IBD is at. (Like, are you improving, stable, or entering a slump). I found that just pain (like, that could be just one bad meal) or energy levels (is it the crohns or a cold coming on?) weren't telling me (ok, pardon the pun) the 'hole' story.
The one thing to keep in mind is that just smaller stool, (or the big 'D') arent' necessarily a sign you are deteriorating. Same goes for bleeding. Like, I've got internal hemmeroids (sp?) that have caused decreased stool size AND bleeding at times (just to keep me on my toes, as if life weren't enough). So don't let that cause you to hit the panic button. If you get into the routine of keeping an eye on what comes out (that sounds gross, doesn't it) you'll soon know what is 'typical' for you, and be better able to gauge what is going on.
Sure beats going in for a colonoscopy every few weeks