There are a number of reasons the J pouch anal anastomosis
fails.
I would say the most common fault would be when the patient is
in pain from constant pouchitis, an inflamed condition of the pouch
which does not abate over a course of time and the pouch owner
choses to have the pouch excised and return to an Ileostomy. Other
reasons include stricture of the join at the anastomosis which
closes off the exit and difficulty in evacuating faeces occurs.
Perforation is another pouch failure condition, the stitched
seam can break open due to force or trauma, the bowel contents then
enter the peritonium, an emergency laparotomy is necessary to
rectify the condition.