Evaluation of myectomized partial-thickness ileum in experimental bladder augmentation.

BACKGROUND: We undertook this study to examine the effects of 'stripping' with excision of serosa and muscularis propria (myectomy) from the antimesenteric aspect of ileum incorporated into the urinary tract. METHODS: Two groups of five dogs were studied. In the first group studied, detubularizing was effected by incising the middle of the thinned antimesenteric aspect of the ileal wall longitudinally. Myectomized bowel was then anastomosed to bladder as a patch-type augmentation cystoplasty. Omentum was applied to denuded surfaces. In the second group of dogs, two isolated segments of ileum were anastomosed to bladder to form cornua with ureters implanted into the cranial ends. One of the two cornua was myectomized as above and, in three of the five dogs, the denuded surfaces were covered by omentum. RESULTS: In the first group, no contraction waves were recorded during filing. In the second group, myectomized segments with adherent omentum were acontractile with low intraluminal pressures and were considerably more capacious compared with control segments and those not omentally wrapped. Ureteric thickening and dilatation were present in all upper tracts proximal to control cornua and myectomized segments not covered by omentum. None of the upper tracts in the first group or above the omentally applied segments in the second group was dilated. Adhesions and back-to-back scarring were seen in stripped bowel which had not been covered by omentum per-operatively. CONCLUSIONS: These findings indicate that myectomy of the antimesenteric aspect of ileum provides a voluminous low-pressure urinary reservoir. Careful application and fixing of omentum to denuded surfaces appears important, it ensures these features by prevention of scarring and adhesion formation.

Intussuscepted partial-thickness ileal valve in continent urinary diversion.

OBJECTIVE: This study was undertaken to ascertain the feasibility of fashioning a nipple valve from partial-thickness ileum and to assess the competence and durability of that valve. The approach employed was designed to circumvent the necessity for considerable lengths of bowel to be committed to valve formation and to avoid the tendency for desusception, present with other forms of nipple valves. METHODS: A technique in which a subterminal segment of partial-thickness ileum was 'skinned' circumferentially of serosa and muscularis propria and then intussuscepted to form a continent nipple-valve mechanism was studied for up to 4 months in 10 dogs. The intussuscepted partial-thickness ileal valve was in continuity with a terminal ileal segment sutured flush with skin and, internally, with another segment laid open and anastomosed to the bladder. RESULTS: All valves were competent, withstanding intravesical pressures up to 90 cm H2O. Six dogs were catheterized, without difficulty, twice daily up to 104 days. The valve mucosal surfaces were smooth due to a loss of plicae circulares, and, between 'back-to-back' submucosal layers, a fine stroma developed. CONCLUSIONS: This simple technique, which is frugal in its use of bowel, provided a robust and effective ileal continence mechanism. Furthermore, because of denervation and interposing fibrous tissue, this nipple valve is considered most unlikely to desuscept subsequently. The intussuscepted partial-thickness ileal valve approach is recommended now for clinical evaluation.