Objective: To investigate the long-term morphological changes in the intestinal segment used to create an orthotopic ileal neobladder.
Materials and methods: Periodic endoscopy with biopsy of the ileal mucosa was performed in 90 patients 3-84 months after radical cystectomy and urinary diversion via an orthotopic neobladder. Three cold-cup biopsies were taken from each patient and mucosal specimens processed for light and electronic microscopy.
Results: Early changes (up to 1 year after surgery) comprised a marked shortening of the villi with loss of microvilli. After 4 years, the prevalent finding was of flat, avillous epithelium that tended to stratify in some areas. The avillous areas were mixed with islets of villous mucosa. There was no dysplasia or malignancy in any of the 90 patients.
Conclusions: Prolonged contact with urine elicited a biphasic response in the ileal mucosa, i.e. an early inflammatory phase, ascribed to the noxious action of urine, followed by a regressive phase in which the epithelium tended to assume a morphology similar to the urothelium. The atrophic changes were almost totally completed after 4 years, although areas with marked modifications alternated with others where the morphology was normal, even many years after surgery. Late changes in the ileal neobladder mucosa appear to be an expression of a functional adaptation of the mucosa to the new environment.