hi Cleos and welcome to healingwell!
if i understood you right, they are not cutting out any part of your bowels, but just taking out a loop and creating the ostomy, right? this should be a very simple procedure. i had a total colectomy on Aug 2009 with ileo-rectal anastomosis due to colon inertia and since it didn't work b/c of my pelvic floor dysfunction + having a slow small intestine, i had a loop ileostomy done July 2010. creating the ostomy alone took only 20 mins! at least that's how it was for me.
the question is what is the purpose of this surgery. i understand that it's first of all to give you relief from your constipation and see whether a loop ileostomy can give you that relief, but are your drs and you hoping that after creating the ostomy your colon will start working again? i know colorectal surgeons and gastro drs have this theory that creating a loop ileostomy will give the bowels a rest and they will start functioning again. i've talked to few ppl who had that done (including my own experience) and it didn't work for us. but maybe there are ppl out there that it did work for them? do you know of any?? if there are, i'm very interested to know.
so if the purpose of your surgery is to see whether the ileostomy gives the bowels a rest and they will start functioning, then maybe that's why your drs want the stools to stay in your colon, so they can see if it starts working and getting rid of the stools..??? i don't know, cuz otherwise why let you stay with all that stuff still stuck inside of your colon, which can make you very uncomfortable. if your colon doesn't start working on it's own arter creating the loop ileo (and i really doubt it will), and you won't be able to rid of the stools, it will be just aweful for you to be left with all that stools in you.
if i were you, i would tell the drs that if they don't mind, i'd rather have the prep and to prescribe me the prep stuff. i wouldn't want to stay with a colon full of it and not being able to ever expel it... even if you have your whole colon perfectly cleaned out before the surgery, it will still continue to produce mucous, so there will always be stuff in there that needs to be expelled anyway. i have only 20 cm of colon (the rectum, which is part of the colon) still there and it produces lots of mucous all the time, but b/c of my pelvic floor dysfunction i can't expel it on my own at all and have to do enemas. but havng your whole 1.5 meters of colon still in - enemas cant clean it all.
i agree with you, going to this surgery w/o doing a prep first doesn't seem right at all to me either. do your best to clean your self out before surgery. i would also advice to go on a low residue/low fiber diet while before the prep (few days-week) and then 2 days before the prep only liquids, then the prep. i wish you the best of luck with the surgery and that everything works out for you.