General geriatrics and gastroenterology: constipation and faecal incontinence.

The incidence of constipation increases with age but no consistent changes of colonic or anorectal motility have been shown in elderly people. Instead, neurological diseases, constipating drugs, bedriddenness and weak straining ability may explain this increased prevalence of constipation. The amount of dietary fibre in the diet may be reduced because of poor chewing ability. Parkinson's disease is accompanied by both slow colonic transit and impaired relaxation of the anal sphincter. Drug-induced constipation is particularly likely with anti-parkinsonism drugs (either anti-cholinergic or dopaminergic) and also with tricyclic anti-depressants, opiates, iron, anti-convulsants and aluminium- or calcium-containing antacids. The prevalence of faecal incontinence is also increased in elderly people. About half of frail bedridden institutionalized patients are incontinent. Anal sphincter pressures tend to be lower, but variables of sensitivity are not. In bedridden people faecal impaction may occur. The ensuing rectal distension leads to relaxation of the internal sphincter and hence to faecal soiling. The condition is often overlooked though correct diagnosis is rather simple, being made with a digital rectal examination.