New approach to surgical treatment of ulcerative colitis and polyposis coli without pelvic pouch. Experimental study in dogs

The ileo neorectal anastomosis: an experimental study on development of the surgical technique and theoretical background

OBJECTIVE

The keystones of surgical treatment of ulcerative colitis and familial adenomatous polyposis are resection of the diseased colon with either an ileostomy or restoration of oro-anal continuity with an ileo-anal pouch. The ileo pouch anal anastomosis however, has a 15-35% pouch-related complication rate, 10% failure rate and is accompanied by an unpredictable functional outcome. In order to reduce these unfavourable rates and to improve functional results an alternative surgical technique, the ileo neorectal anastomosis (INRA), was developed experimentally.

MATERIALS AND METHODS

In an experimental study 12 Yorkshire-Dutch landpigs had a subtotal colectomy and rectal mucosectomy. Subsequently a vascularized ileal mucosa sling was created and transposed on to the denuded rectal muscular cuff in eight. In another four animals a non-vascularized mucosa sling was transposed. The covering ileostomy was closed after 3 weeks. Repeated endoscopies, histological examinations of mucosal biopsies and rectal compliance measurements were carried out to evaluate the functional result of the neorectum.

RESULTS

The surgical procedure of the INRA was technically successful in this animal study. Repeated endoscopy and histology showed complete ileal mucosa ingrowth in the neorectum without severe fibrosis in the group of animals with a vascularized sling. At follow up after 1 year no colonic metaplasia had occurred. Measurements of the neorectal reservoirs in the group of animals with a vascularized INRA procedure showed a median 'maximum tolerated volume' of 338 ml (range 300-410 ml).

CONCLUSION

The INRA is technically feasible and reproducible. The histologically proven survival of the vascularized ileal mucosa and development of a compliant neorectal reservoir make the INRA an interesting alternative restorative procedure. Avoidance of the pouch-related complications of the ileo pouch anal anastomosis by this procedure might herald a new era of restorative surgery.

Straight ileoanal anastomosis after longitudinal strip myectomy in the swine model

In an attempt to improve the function of the straight ileoanal anastomosis, an experimental study was performed using the swine model. The terminal ileum was altered by completely removing two longitudinal strips of muscle prior to performing a straight ileoanal anastomosis. The intent of the study was to determine whether muscle stripping was technically possible and whether bowel thus treated would remain viable to passively form a pelvic reservoir. The length of time required for formation of the reservoir was noted. All animals survived the procedure to allow evaluation. The muscle stripping was not difficult to perform. Viability was not a problem since the myectomy animals thrived well and demonstrated continence, weight gain, and reservoir formation. The results are encouraging. It appears that strips of muscularis propria can be removed from the terminal ileum without jeopardizing its viability. This seems to disrupt sufficiently the tonus of the bowel to allow better function of the straight ileoanal anastomosis through formation of a passive pelvic reservoir within a month's time in the swine model, and it may have application in the human.