Here's what I know: The rectum is sometimes left (with an ileo op - especially for non-cancer diseases) for various reasons. The potential for a J-pouch is one ... you need the rectum if you are contemplating that. Even patients that say to their docs that they are not thinking of going J ... especially if they are young, once the surgeon gets in there and sees the rectum looks healthy - the rectum is often left. Leaving that option open for a J pouch.
Taking the rectum out in the same operation ... adds hours to an already lengthy op. In my case this was the main reason the rectum was left when I had my ileo ... I was not doing well during surgery and they wanted to close me up and get me off the table asap.
I'm sure there are other reasons too -- there are quite a few of us that woke up with our rectums inactive but still there
Found out yesterday ... to remove my rectum I had a Single Incision Laparascopic Protectomy - Sphincter Sparing. It's a finicky op ... not all surgeons feel comfortable doing it - rectum removal is most often done 'non-laparascoptically'. Reason sphincter was left ... it is a helpful muscle to stabilize the pelvic floor.
Today I'm going to start decorating outside (we're Griswold wannabes) ... feeling so good!
Have a wonderful day, all!