Gastric muscularis as a urinary sphincter

To test the ability of gastric muscularis to act as a urinary sphincter in a rat model system.

Fourteen Long-Evans rats had an ileal conduit constructed joining the bladder to the ventral skin, creating urinary incontinence. A segment of gastric muscle maintained on its vascular pedicle was encircled around the conduit. The first 7 animals (group A) had both conduit and sphincter constructed simultaneously, whereas the remaining 7 animals had the conduit constructed first, followed by a two-week period of observation, after which gastric sphincters were added (group B). All animals were observed for urine leakage via the cutaneous stoma. At two weeks after sphincter placement, all animals underwent surgical exploration, pressure profilometry of the conduit, and histologic examination of the sphincter zone.

Pressure profilometry demonstrated elevated pressures in the sphincter zone relative to baseline pressures in the conduit of all animals (group A: mean baseline, 4.8 cm water, mean maximum, 20.6 cm water; group B: mean baseline, 5.2 cm water, mean maximum, 18.1 cm water). At exploration, no intra-abdominal complications were noted in 13 of 14 animals. All conduits were easily catheterizeable and were found to be continent after they had been filled to capacity. The ileum and gastric segments were histologically found to be viable with no evidence of necrosis or ischemia.

These preliminary results suggest that gastric muscularis may be a potential substitute urinary sphincter in the management of sphincteric urinary incontinence.