Morphologic Changes in Ileal Reservoir Mucosa after Long-Term Exposure to Urine: A Study in Patients with Continent Urostomy (Kock Pouch)

Abstract

In patients with supravesical urinary diversion, continent ileal reservoirs utilized for urinary collection were examined by endoscopy at intervals of 1 month to 9 years after surgical construction, and biopsy specimens were obtained for light microscopy and morphometry. The gross appearance of the mucosa showed alterations in the shape of the shorter and broader finger-like villi during the first postoperative month to the subsequent very low ridges and convolutions or, in some instances, flat mucosa devoid of individual villi. Starting between 1 and 3 years after the surgical construction, endoscopically smooth areas were encountered in caudal areas of the reservoir, and the areas were mixed with islands of villous mucosa. Microscopically and morphometrically, the specimens from villous areas confirmed reduction in villous height and increase in crypt depth, whereas no changes were seen in the epithelial mitotic frequency. The number of mucus-storing goblet cells increased already within 1 month after construction. Specimens obtained from smooth areas showed alterations in the intestinal structure, with reduction of crypts, decreased height of epithelial cells, and occasional epithelial denudation. No signs of fibrosis, foreign-body reaction, or dysplasia were encountered. The constant exposure to urine leads to adaptive changes of the reservoir mucosa, resulting in a true atrophy of villi, crypts, and individual epithelial cells.