Internal Sphincter Dysfunction: A Cause of Idiopathic Megacolon

Abstract

Constipation is defined as the infrequent and incomplete passage of faeces per rectum. Megacolon is an uncommon condition in which the bowel is persistently of increased diameter, and is always associated with long-standing constipation (Todd 1961). Two main groups are recognised according to whether or not ganglia are present in the inter- muscular plane of the rectal wall. Their complete absence, even along a short segment of rectum, denotes Hirschsprung’s disease. If ganglia are present the dilated bowel may be secondary to some predisposing factor (Todd 1961), or there may be no apparent organic reason as to why the bowel should be so dilated. This latter condition is termed idiopathic megacolon (Lane and Todd 1977).