Aspects of colonic motility in idiopathic slow transit constipation
This thesis sets out to examine the hypothesis that some patients with idiopathic constipation, notably those who develop their symptoms following childbirth or hysterectomy, have regional as opposed to total colonic dysmotility. Such a group may be amenable to segmental rather than total colonic resection. Several clinical studies are presented which establish postchildbirth/hysterectomy constipation as a distinct subgroup of idiopathic constipation. Studies of gastric emptying demonstrate that patients with postchildbirth/hysterectomy constipation have normal motility in the proximal gastrointestinal tract. In contrast, patients with idiopathic constipation have prolonged gastric emptying indicating that proximal GI dysmotility may form a significant component of the presenting symptoms. Having identified that the proximal GI tract appears normal in patients with postchildbirth/hysterectomy constipation the next task was to identify in which region of the colon the dysmotility was most severe. Segmental colonic transit studies, using radio-opaque markers, identify delayed transit in the left colon, while dynamic radio-isotope studies localise the area of abnormality to the sigmoid colon. Colonic manometry studies, using a water-perfusion catheter point to a region of hindgut dysmotility which manifests as an excess of low pressure waves at rest and a specific failure to generate high pressure propagative waves. The usefulness of prostigmine provocation testing is examined critically in this group of patients and the pitfalls of this technique are presented.