Effect of sex on perception of rectosigmoid stimuli in irritable bowel syndrome

In irritable bowel syndrome (IBS) patients, the relationship between sex and sensitivity to visceral stimuli is incompletely understood. Our aim was to evaluate the effect of sex on perceptual responses to visceral stimulation in IBS. Fifty-eight IBS patients (mean age 42 +/- 1 yr; 34 men, 24 women) and 26 healthy controls (mean age 38 +/- 3 yr; 9 men, 17 women) underwent barostat-assisted distensions of the rectum and sigmoid colon. Rectal discomfort thresholds were measured using a randomized, phasic distension paradigm before and after repeated noxious sigmoid stimulation (SIG, 60-mmHg pulses). Sex had a significant effect on rectal discomfort thresholds. Women with IBS were the most sensitive ( lower thresholds [27 +/- 2.7 mmHg] and higher ratings), with significantly lower rectal discomfort thresholds compared with men with IBS (38 +/- 2.3 mmHg) and healthy women who were the least sensitive (41.9 +/- 3.2 mmHg; both P < 0.01). There were no significant differences in rectal discomfort thresholds between healthy men (34 +/- 4.3 mmHg) and men with IBS. Across both IBS and control groups, women demonstrated a significant lowering of discomfort thresholds after noxious sigmoid stimulation (P < 0.01), while men did not. Sex significantly influences perceptual sensitivity to rectosigmoid distension. Women show greater perceptual responses to this paradigm.