This is called an ileo-rectal anastomosis. If I recall correctly they were more common before J-pouches were developed. It’s a strange procedure to suggest for IBD, I think, whether you have UC or Crohn’s colitis, since it leaves behind the entire rectum, which can readily develop inflammatory symptoms. I think the results may not be as good as J-pouch results, on average, but I haven’t double-checked that. My reading of the literature on indeterminate IBD is that a J-pouch is the procedure of choice, and that’s what I chose 16 years ago. If your surgeon lacks the necessary experience and skills, it’s best to consult a more experienced surgeon. If your surgeon has a good reason for suggesting an IRA instead of a J-pouch, he ought to tell you what it is.