Abdominal symptoms and anorectal function in health and irritable bowel syndrome

Background: It is unclear how the quality and quantity of abdominal symptom s and anorectal function differ between irritable bowel syndrome (IBS) pati ents and healthy controls, and whether different anorectal function in pati ents is associated with abdominal symptoms in IBS. Methods: Fifty-two outpa tients with IBS and 12 healthy controls kept daily symptom records over 1 w eek. At the end of the week, anorectal function was assessed by manovolumet ry before and after a standard fatty meal. Patients were divided into sympt om and manovolumetric subgroups using a cluster analysis and also into thos e below (hypersensitive) and those within (normosensitive) the 95% confiden ce interval of the controls mean for maximal tolerable distension (MTD). Re sults: Regardless of subgroup, the patients were distinguished from the con trols by pain, bloating, straining and incomplete evacuation. Compared with controls, MTD was lower in the pain/bloating subgroup characterized by con siderable pain and the bowel habit subgroup characterized by hard stools, v ariable stool consistency and heavily disturbed stool passage. Preprandial rectal hypersensitivity was highly prevalent in this bowel habit subgroup. No similar association with the pain/bloating subgroup was found. Patients and controls showed a significant and similar postprandial decrease in MTD. Conclusions: IBS is distinguished from health by pain, bloating, straining and a feeling of incomplete evcuation. Baseline rectal hypersensitivity is associated with constipation-like bowel habit, increased rectal sensitivit y after a meal and/or preceding distension is a normal reaction unimportant in the genesis of symptoms in IBS.