Mucosal alterations in pelvic ileal reservoirs. A histological and ultrastructural evaluation in an experimental model.

To study mucosal changes in ileal pouches, three different types of pelvic ileal reservoir (2-loop, 3-loop and 4-loop), interposed in place of resected rectum, were constructed in 12 piglets, 4 animals in each group (n = 12). After a 6 week interval the animals were sacrificed and the reservoirs removed and processed for light and scanning electron microscopy (SEM). Both acute and chronic inflammatory changes were present but not prominent in the pouch mucosa. With the exception of mucosal ulcers both the histological and SEM-findings greatly resembled the atrophic, flat mucosa seen in ileal coeliac disease. Macroscopic findings did not correlate with histological findings. Colonization by bacteria and bacterial overgrowth were noticed in every pouch suggesting a possible link between bacterial invasion and pouch ileitis. No correlation was found, however, between the amount of intraluminal bacteria and the severity of the pouchitis.