The physic-pathology of continence and anti-reflux mechanisms

Abstract

– When performing a heterotopic continent urinary diversion there are some crucial moments from a physiopathological point of view, such as the reconfiguration of the low-pressure reservoir, the uretero-enteric anastomoses and making the valve for continence. The low-pressure reservoir is achieved by detubularising an intestinal segment, chosen for its natural characteristics of peristalsis, the possibility of residual contractions and the tensive-elastic features of the tract used. It is traditionally thought that it is the shape given to the neo-reservoir rather than the length of intestinal tract which influences compliance. In turn the uretero-enteric anastomoses should not be assessed purely surgically, but also physiologically for their capacity to preserve renal functionality and prevent reflux. Correctly performed anastomoses adapted to the single techniques of continent diversion are extremely important, bearing in mind parameters such as the length of the intramural tract and the calibre of the ureters. The linchpin, however, is the continence mechanism, achieved by using valves that are physiologically present (ileocecal valve) or by constructing valves from intestinal segments. Careful evaluation of the various methods for this purpose, from the flutter valve to Mitrofanoff's principle, highlights the diversity of these mechanisms, due to different pressor balances, and of their validity and reliability, both physiopathologically and with regard to long-term continence. The outcome is that the choice of intestinal segment to be used, the type of reconfiguration, the uretero-entero anastomosis and the valvular mechanism techniques are not casual and/or preferential, but based each time on pressure factors present in the type of urinary diversion.