Background: Pouchitis appears to be the most common complication after restorative proctocolectomy.
Material/Methods: In experimental models we investigated the correlation between the width of anastomosis and the frequency of pouchitis. Twenty-three Wistar rats underwent restorative proctocolectomy under pentobarbital anesthesia. Normal width anastomosis was performed in 11 animals (Group I). In the remaining 12 animals (Group II) the diameter of anastomosis was reduced by 50%. All animals were sacrificed and the pouch mucosa was histologically (Moskowitz score) and immunohistochemically (IL-1, IL-6, IL-10, IL-12 expression) examined.
Results: Morphological assessment of pouchitis symptoms based on Moskowitz scale revealed considerably more severe inflammation (p=0.0079) in the animals from Group II than in the rats from Group I. The expressions of investigated cytokines, assessed qualitatively in histopathological examination, were higher in rats with narrow anastomosis in comparison with animals with normal anastomosis.
Conclusions: The stricture of anastomosis increases the intensity of pouchitis and stimulates the production of interleukins. It seems that anastomotic stricture plays an important role in the development of pouchitis.

Keywords: Interleukins - metabolism, Ileum - surgery, Constriction, Pathologic, Colonic Pouches - adverse effects, Anastomosis, Surgical - adverse effects, Anal Canal - surgery, Pouchitis - pathology, Rats, Wistar