Pathogenesis of urgency in defaecation in Crohn's disease.

In 39 patients with Crohn's disease with 20 suffering from urgency in defaecation, the degree of proctitis, anal basal and squeeze pressures and anal sphincter responses to passive rapid or slow rectal filling were not correlated to the presence or absence of urgency or its severity. However, there was a positive correlation between urgency and both defaecation frequency and looseness of stools as well as extent of disease, with invariable involvement of the small intestine in urgency patients. Disease confined to the colon was found only in non-urgency cases. It was proposed that extensive disease involving both the small and large intestine could elicit abnormal bowel motility, and lead to unusually rapid rectal filling, inevitably followed by rapid reflex relaxation of the anal sphincter, manifesting itself as urgency. This hypothesis would be consistent with the observation that operative removal of diseased bowel with ileorectal anastomosis may abolish urgency.