How consistent is the anal transitional zone in the double-stapled ileoanal reservoir?

The double-stapled ileoanal reservoir (DSIAR) has become a preferred method for ileal pouch anal anastomosis in restorative proctocolectomy. This investigation assessed the relative ratio of epithelial tissue types within the anal transition zone after a DSIAR and reviewed functional physiological differences.

All 138 patients who underwent restorative proctocolectomy with a DSIAR for mucosal ulcerative colitis were stratified into two groups according to histological evidence of epithelium types in the distal excised rectal donut. In group I a squamous or a squamous mixed with columnar epithelium was present (n=40) whereas in group II only columnar epithelium was seen (n=98). Anal physiological parameters were measured by anal manometry preoperatively, prior to ileostomy closure, and 1 year after surgery.

None of the preoperative resting and squeeze pressure parameters showed a significant difference between the two groups. Postoperative mean and maximal resting pressures were significantly decreased in both groups. Postoperative mean and maximum squeeze pressures were decreased in group I. Postoperative mean length of the high-pressure zone tended to be decreased in both groups. The decrease in rectoanal inhibitory reflex was significant in both groups. Postoperative functional parameters measured as maximal tolerable volume and compliance were significantly improved from preoperative values in both groups.

The tissue type in the anal transitional zone after DSIAR has a wide variability at a similar level (height) of the anastomosis. However, these different epithelial types were not associated with substantial physiological functional differences. Thus, if technically feasible, it is desirable for DSIAR to construct the anastomosis as close to the dentate line as possible.