Failed ileoanal anastomosis: correlations between clinical function and anal canal neurophysiologic and histologic examinations.

Ten patients with an ileoanal anastomosis had conversion to permanent ileostomy 13 (range, 6-29) months after the primary procedure. Causes for reoperation were incontinence in seven patients, unacceptable stool frequency without incontinence in two patients, and atypia in the mucosal remnant with perfect continence in one patient. Stool frequency, continence function, anal canal resting pressure, external anal sphincter (EAS) EMG/pressure relationship (in terms of slope, m), EAS fiber density (FD), and pressure in the distal ileum were registered, and the mucosa and the anal sphincter muscles were examined histologically. There were significant correlations between continence function and EAS changes in terms of both neurophysiologic tests (m and FD) and the histologic picture. The abnormalities in six incontinent patients were consistent with denervation of the EAS. The main reason for fecal leakage in one patient was the high amplitude of pressure waves in the distal ileum. Preservation of mucosal epithelium proximal to the dentate line per se did not seem essential to maintain continence.