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BACKGROUND Magnetic resonance imaging (MRI) of the colonic response to a macrogol challenge drink can be used to assess the mechanisms underlying severe constipation. We measured the intrasubject reproducibility of MRI measures of colonic function to aid their implementation as a possible clinical test. METHODS Healthy participants attended for MRI on two occasions (identical protocols, minimum 1 week apart). They underwent a fasted scan and then consumed the macrogol drink. Subjects were scanned at 60 and 120 minutes, with maximum value reached used for comparison. The colonic volume, water content, mixing of colonic content and the movement of the colon walls were measured. Coefficients of variation and intraclass correlation coefficients (ICC) were calculated. RESULTS Twelve participants completed the study: nine female, mean age 26 years (SD 5) and body mass index 24.8 kg/m2 (SD 3.2). All measures consistently increased above baseline following provocation with macrogol. The volume, water content and content mixing had good intrasubject reproducibility (ICC volume = 0.84, water content = 0.93, mixing = 0.79, P

Background High-resolution manometric studies below the stomach are rare due to technical limitations of traditional manometry catheters. Consequently, specific motor patterns and their impact on gastric and small bowel function are not well understood. High-resolution manometry was used to record fed-state motor patterns in the antro-jejunal segment and relate these to fasting motor function. Methods Antro-jejunal pressures were monitored in 15 healthy females using fiber-optic manometry (72 sensors at 1 cm intervals) before and after a high-nutrient drink. Key results Postprandial motility showed a previously unreported transition point 18.8 cm (range 13-28 cm) beyond the antro-pyloric junction. Distal to the transition, a zone of non-propagating, repetitive pressure events (11.5 ± 0.5 cpm) were dominant in the fed state. We have named this activity, the duodeno-jejunal complex (DJC). Continuous DJC activity predominated, but nine subjects also exhibited intermittent clusters of DJC activity, 7.4 ± 4.9/h, lasting 1.4 ± 0.55 minutes, and 3.8 ± 1.2 minutes apart. DJC activity was less prevalent during fasting (3.6 ± 3.3/h; P = .04). 78% of fed and fasting state propagating antro-duodenal pressure events terminated proximally or at the transition point and were closely associated with DJC clusters. Conclusions and inferences High-resolution duodeno-jejunal manometry revealed a previously unrecognized transition point and associated motor pattern extending into the jejunum, consistent with the duodenal brake previously identified fluoroscopically. Timing suggests DJC activity is driven by chyme stimulating duodenal mucosal chemosensors. These findings indicate that the duodenum and proximal jejunum consists of two major functional motor regions.

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder which represents a major cost to health-care services. The diagnosis of IBS is currently performed by means of symptom-based diagnostic criteria, but there has been an ongoing interest in developing biomarkers which could simplify the diagnosis and/or evaluating the effect of treatments. This article reviews the current literature concerning the proposed biomarkers including those of altered gut motility, of visceral hypersensitivity, of abnormal brain mechanisms, of serum, fecal and mucosal inflammation and of increased intestinal permeability.

While the pharmacological armamentarium for chronic constipation has expanded over the past few years, a substantial proportion of constipated patients do not respond to these medications. This review summarizes the pharmacological and behavioral options for managing constipation and details the management of refractory constipation. Refractory constipation is defined as an inadequate improvement in constipation symptoms evaluated with an objective scale despite adequate therapy (ie, pharmacological and/or behavioral) that is based on the underlying pathophysiology of constipation. Minimally invasive (ie, rectal irrigation and percutaneous endoscopic colostomy) and surgical therapies are used to manage refractory constipation. This review appraises these options, and in particular, percutaneous endoscopic colostomy, which as detailed by an article in this issue, is a less invasive option for managing refractory constipation than surgery. While these options benefit some patients, the evidence of the risk: benefit profile for these therapies is limited.