Role of faecal gas analysis for the diagnosis of IBD.

The diagnosis of IBD (inflammatory bowel disease) is based on the clinical evaluation of symptoms and signs leading to a series of investigations. The investigations used are often unpleasant for patients; they are invasive, costly and potentially dangerous. Patients often report that the odour of flatus, or the gas emitted from faeces, is abnormal during a flare of their IBD. Our group has characterized the VOCs (volatile organic compounds) in the headspace gas emitted from faecal samples from healthy subjects, from patients with infectious diarrhoea and from those with Crohn's disease or ulcerative colitis, both in relapse and remission. Painstaking analysis of gas chromatography-MS data (VOC profiling) has revealed patterns of compounds that are strongly associated with specific infectious diseases and with IBD. These compounds represent a change in the microflora and/or the metabolism of bacteria and/or the epithelium in disease states. These profiles offer a potential for rapid non-invasive assessment of a range of infectious and non-infectious gastrointestinal diseases. The study of VOCs may lead to a better understanding of the pathogenesis of IBD.