[Motility disorders of the colon]

The motility of the colon is modulated by the enteric nervous system. It is very complex, governing backward and forward movements of the feces. Primary megacolon and megarectum are clinically diverse. Megacolon refractory to laxative treatment may be subject to colectomy, while megarectum should be treated by consistent laxation. Acute colonic pseudo-obstruction may occur with severe systemic diseases and electrolyte disturbances or it may be postoperatively and/or medically induced. A small proportion of chronically constipated patients suffer from slow transit constipation, others from disordered defecation. In the remaining patients no objective cause of the complaints may be found. In slow transit constipation, propulsive colonic motility is disturbed, dietary fiber is ineffective, and the response to bisacodyl is blunted. Pelvic floor dyssynergia is characterized by a voluntary (although unconscious) contraction of the anal sphincter simultaneously with the abdominal muscles. It can be treated by avoiding straining and by sphincter training.