The critical level for preservation of continence in the ileoanal anastomosis.

Mucosal proctectomy with ileoanal anastomosis was performed for 90 patients with ulcerative colitis or polyposis over the past 18 years. In three, the anastomosis was at the dentate line. All three had varying degrees of soilage necessitating permanent ileostomy in one. For 12 patients with the anastomosis 1.0 cm proximal to the top of the columns, all were totally continent, but six experienced recurrent disease. For 75 in the third group, the anastomosis was at the top of the columns. Five await ileostomy closure. Of the other 70, none experienced recurrent disease and three have mild nighttime soilage, two of which are less than 1 year following operation. We recommend that the transitional epithelium of the anorectal columns be preserved.