Abnormalities of left colonic motility in ambulant nonconstipated patients with irritable bowel syndrome.

Our objective was to evaluate left colonic motility patterns recorded under physiological conditions during 24 hr in fully ambulant nonconstipated IBS patients compared to healthy controls. A 42-hr manometry of the left colon was performed in 11 nonconstipated IBS patients and 10 age- and sex-matched healthy volunteers. On day 1, a 6-channel, 10-cm interval, solid-state catheter was positioned. Frequency, amplitude, and motility index (MI) of segmenting pressure waves in the descending and sigmoid colon were calculated during the 24-hr study period on day 2. High-amplitude propagated contractions (HAPCs) were identified visually and their characteristics were calculated. In IBS patients a higher frequency of segmenting pressure waves was observed in the sigmoid colon compared to the descending colon (P = 0.006). In contrast, no regional differences were observed in controls. Awakening (P = 0.048) as well as having a meal (P = 0.024) was associated with a smaller increase of contraction frequency in the descending colon of IBS patients compared to controls. HAPCs occurred more frequently in IBS patients than in controls (P = 0.035). HAPCs in IBS patients reached a more distal colonic level and occurred more frequently in clusters. Defecation in IBS patients, but not in controls was always preceded by a cluster of HAPCs. In conclusion, left colonic segmenting pressure waves and HAPC characteristics are altered in nonconstipated IBS patients.