Is the Colonic Response to Food Different in IBS in Contrast to Simple Constipation or Diarrhea Without Abdominal Pain?

Colonic response to food (CRF) is abnormal in irritable bowel syndrome (IBS) patients. The aim of this study was to compare CRF in patients who complain of abnormal defecation pattern according to the presence or absence of abdominal pain. One hundred forty-nine patients and 50 controls were studied: 96 IBS patients (46 IBS-C, 13 IBS-D, 15 IBS-M, and 22 IBS-U not included), 43 patients with functional constipation (group C) and ten with functional diarrhea (group D). Clinical evaluation and visual analog scales about four items (constipation, diarrhea, abdominal bloating and abdominal pain) were filled by all subjects. Colonic transit time (CTT) was measured in fasting conditions and after eating a standard 1,000-cal test meal. CRF was quantified by calculating the variation in number of markers between the two films. The frequency of meal-related symptoms did not vary among the different groups of patients but was significantly higher than in controls. Compared to IBS-C patients, constipated patients of the group C had longer total and segmental colonic transit time, and compared to IBS-D patients, diarrheic patients of the group D had shorter oro-anal and segmental colonic transit time except in the recto-sigmoid area. CRF was different in patients and controls, and differed between IBS and non IBS patients with similar transit abnormalities. Stool output was greater in patients of the group D than in patients of the IBS-D group. The different subgroups of IBS patients have different CRF patterns, distinct from subjects with constipation and diarrhea, but without abdominal pain.