Background: The relationship of small-bowel dysmotility to dietary intake in irritable bowel syndrome (IBS) is obscure.
Methods: This study evaluated postprandial jejunal motility in IBS patients classified as constipation-predominant (n = 25) or diarrhoea-predominant (n = 35) and compared results against 18 volunteers. Twenty-four-hour ambulatory jejunal manometry was carried out in all subjects, and recordings were analysed by microcomputer and visual assessment.
Results: By means of analysis of variance (fitting factors for channels, meals, and time periods) postprandial contraction frequency was greater in both patient groups compared with normal (constipation-predominant versus normal, diarrhoea-predominant versus normal; P < 0.001). In the constipation-predominant cohort, contraction amplitudes were lower (constipation-predominant versus normal; P < 0.002). Discrete cluster contractions occurred with similar frequency and duration in both patient and volunteer groups.
Conclusions: Quantitative differences of postprandial jejunal contraction characteristics have been shown between patients with IBS and healthy volunteers. Contraction frequency is greater than normal in both diarrhoea- and constipation-predominant categories, whereas contraction amplitudes are lower in constipation-predominant patients.