Prevalence of rectal hypersensitivity in patients with irritable bowel syndrome and its clinical subgroups.

AIM: To evaluate the prevalence of rectal hypersensitivity in our irritable bowel syndrome (IBS) patients, the relationship of hypersensitivity to rectal distensibility and the differences in sensitivity among clinical subgroups of IBS. MATERIAL AND METHODS: 18 healthy subjects and 56 IBS patients (Rome-II criteria; 22 diarrhea-predominant, 15 constipation-predominant and 19 alternating). Rectal sensitivity and distensibility were studied by isobaric phasic distension of a poliethilene bag with a barostat. RESULTS: IBS patients showed a lower threshold for discomfort, pain and maximum tolerate distension, without any differences in rectal distensibility. 64% of IBS patients were hypersensitive. 89% of patients with alternating IBS were hypersensitive while only 68% and 26% of patients with diarrhea-predominant IBS and constipation-predominant IBS, respectively, were. There were no differences in rectal distensibility between hypersensitive and normosensitive patients. CONCLUSION: 64% of our IBS patients show rectal hypersensitivity, apparently not related to rectal distensibility. Hypersensitivity is mostly found in alternating IBS patients, and rare in constipation-predominant IBS.