RECTAL HYPERSENSITIVITY IN THE IRRITABLE-BOWEL-SYNDROME

Studies of rectal sensory thresholds and compliance in patients with t he irritable bowel syndrome have produced conflicting results though t here is persistent evidence of rectal hypersensitivity particularly in those with diarrhoea-predominant symptoms. This study examined rectal sensation and compliance in 31 patients with constipation-predominant irritable bowel syndrome (mean age 41 years, 27 female) and 17 health y volunteers (mean age 45 years, 17 female). A rectal balloon was infl ated with fluid at a constant rate and the volume and intrarectal pres sure at sensory thresholds was recorded. The volumes at first (129 +/- 8 vs 229 +/- 24 ml, P < 0.001 Mann-Whitney-U test), constant (159 +/- 12 vs 286 +/- 21, P < 0.001) and maximum tolerated sensation (290 +/- 13 vs 509 +/- 19, P < 0.001) were all significantly less in the irrit able bowel group. There was no significant difference in intrarectal p ressures at any of these volumes (29.0 +/- 2.2 cmH(2)O vs 29.0 +/- 2.5 , 35.0 +/- 2.5 vs 34.0 +/- 2.8, 71 +/- 2.5 vs 65.0 +/- 3.0 respectivel y). Rectal compliance was significantly less in the irritable bowel gr oup (3.6 +/- 0.2 ml/cmH(2)O vs 8.7 +/- 0.4, P < 0.001). Twenty two pat ients complained of abdominal pain on balloon inflation, mimicking tha t experienced as part of their symptoms. Patients with constipation-pr edominant irritable bowel syndrome have rectal hypersensitivity and re duced compliance.