Large Intestine

Aging does not appear to cause major changes in colonic or anorectal motility. Rectal compliance and tone are normal, but the perception of anorectal distention is reduced in the elderly. This reduction in rectal wall sensitivity, together with a modest delay in colonic transit, may play a role in constipation.

Fecal incontinence occurs in up to 50% of nursing home residents. Common causes are constipation with fecal impaction, laxative use, neurologic disorders (eg, autonomic neuropathy), anorectal surgery or previous obstetric injury, and colorectal disorders (eg, rectal prolapse or radiation injury). Fecal incontinence is often a feature of diarrheal illness but the two may occur separately.

The incidence of diverticulosis increases with aging because of declining tensile strength in the smooth muscle of the colonic wall. Ischemic colitis occurs almost exclusively in the elderly as a result of mesenteric atherosclerosis. Inflammatory bowel disease, often regarded as a disease of young adults, has a smaller incidence peak in adults in their 50s through their 80s (mainly ulcerative colitis) and is more likely to be limited to more distal colonic segments. However, the initial presentation may be severe and associated with complications (eg, toxic megacolon).

This topic was last updated May 2005.