Colonic response to laxative ingestion as assessed by MRI differs in constipated irritable bowel syndrome compared to functional constipation

Abstract

BACKGROUND: Functional constipation (FC) and irritable bowel syndrome with constipation (IBS-C) share many symptoms but underlying mechanisms may be different. We have developed a magnetic resonance imaging (MRI) technique to measure intestinal volumes, transit, and motility in response to a laxative, Moviprep( R) . We aim to use these biomarkers to study the pathophysiology in IBS-C and FC., METHODS: Twenty-four FC and 24 IBS-C were studied. Transit was assessed using the weighted average position score (WAPS) of five MRI marker pills, taken 24 h before MRI scanning. Following baseline scan, participants ingested 1 L of Moviprep( R) followed by hourly scans. Magnetic resonance imaging parameters and bowel symptoms were scored from 0 to 4 h., KEY RESULTS: Weighted average position score for FC was 3.6 (2.5-4.2), significantly greater than IBS-C at 2.0 (1.5-3.2), p = 0.01, indicating slower transit for FC. Functional constipation showed greater fasting small bowel water content, 83 (63-142) mL vs 39 (15-70) mL in IBS-C, p 230 min distinguishes FC from IBS-C with low sensitivity of 55% but high specificity of 95%., CONCLUSION & INFERENCES: Our objective MRI biomarkers allow a distinction between FC and IBS-C. Copyright © 2016 The Authors. Neurogastroenterology & Motility published by John Wiley & Sons Ltd.