The role of the ileal conduit in the development of upper tract dilatation.

The purpose of this study was to clarify the role of the conduit in the development of upper tract dilatation after ileal conduit urinary diversion. Twenty-seven patients with a normal upper tract were compared with 17 who had developed upper tract dilatation. Patients were studied by means of a technique to measure pressure and flow under "steady-state" conditions. Pressure activity was classified into two types. Type I pressure activity (frequency 6.2 +/- 3/min; amplitude 4.7 +/- 3 cm H2O) resulted in to-and-fro movement of contrast and the escape into the appliance of small volumes of contrast. In controls, most of the output from the conduit occurred during type I activity (73 +/- 14%). Type III/IV pressure activity resulted in vigorous aboral peristalsis and occurred infrequently in controls (frequency 5 +/- 4/h). In patients with upper tract dilatation, in contrast, type III/IV peristaltic activity occurred frequently (frequency 37 +/- 30/h; P less than 0.001: amplitude 72 +/- 34 cm H2O) and was responsible for most of the output (70 +/- 17%; P less than 0.001). The findings support the hypothesis that high pressure activity in the conduit is an important factor in the aetiology of upper tract dilatation, and they are compatible with the presence in such patients of functionally important obstructions of the distal conduit.