Anorectal function after long-term transanal colonic irrigation

The increased use of transanal colonic irrigation (TAI) warrants study of its effects on anorectal function after long term use.

Anorectal physiology tests were performed in 12 patients with chronic idiopathic constipation (CC) and 10 with idiopathic faecal incontinence (FI) [median 55 years (range 21-70)] before and after a median 68 (range 32-113) months use of TAI.

In CC median, urge rectal volume increased from 121 (70-264) to 268 ml (69-484) (P = 0.05) whereas rectal compliance, volume at first sensation, maximum tolerable rectal volume, anal sensory level, median anal resting and squeeze pressures were unaltered. In FI median, urge volume increased from 125 (range 50-221) to 158 ml (range 97-287) (P = 0.033) and maximum tolerable volume increased from 156 (80-321) to 253 ml (162-332) (P = 0.047). Median anal resting pressure decreased from 48 (29-100) to 32 cmH(2) O (12-79) (P = 0.011) and anal squeeze pressure decreased from 69 (30-107) to 38 cmH(2) O (30-70) (P = 0.017). Rectal compliance, volume at first sensation and anal sensory level were unaltered.

As rectal compliance was unaltered, it is likely that the increased rectal tolerable volume is explained by patients adapting to irrigation rather than by changes in the property of the mechanical rectal wall. As anal sphincter function was deteriorated only in FI, we suggest that this is because of the natural history of FI rather than any effect of long term TAI.