“…2,3 Even though altered rectal perception has been proposed to be a biological marker of IBS, 4,5 the diagnosis still relies upon diagnostic criteria and normal findings on routine clinical investigations. 1,6 The bowel habits in IBS patients show considerable inter-and intra-individual variability, 7 and it has been common-place to use supporting symptom criteria to divide IBS patients into different subgroups based on their predominant bowel pattern. This has been important especially in drug trials, where a positive effect could be expected only in subgroups of patients, whereas side effects could be expected in other patients, based on the physiological mode of action of the drug.…”