Due to a lack of reliable biological markers, the diagnosis of irritable bowel syndrome (IBS) is based on symptom criteria. The possible physiological correlates of these criteria are not known. Our aims were to identify correlations of currently used IBS symptom criteria with distinct alterations in visceral perception.
Forty-two IBS patients (51% women) with a mean age of 39.5+/-1.4 yr, were included; 64% of patients were recruited from advertisement and 36% were clinic referrals. Patients completed a bowel symptom questionnaire, which included the Rome criteria and symptom severity ratings. Rectal discomfort thresholds were evaluated in all patients and in 19 controls, using a nonbiased tracking protocol consisting of phasic rectal balloon distensions before (PreTh) and after (PostTh) repetitive, high-pressure sigmoid distensions. We assessed the effect of each Rome criteria and symptom severity on PreTh and PostTh.
IBS symptom severity was reported as moderate in 38.1% and as severe in 61.9% of patients. Overall, lower thresholds were observed in IBS patients than in controls (PreTh: 28.2+/-1.7 vs. 36.3+/-2.8 mm Hg, p<0.05; PostTh: 25.3+/-1.5 vs. 34.2+/-2.7 mm Hg, p<0.01). When assessing the effect of Rome criteria on rectal thresholds, we found that patients with hard/lumpy stools had lower thresholds than those without them, whereas patients with loose watery stools had higher thresholds than those who lacked them (both p<0.05). The lowering of rectal discomfort thresholds after sigmoid stimulation was observed regardless of the presence or absence of any Rome criteria or symptom severity.
Although a decrease in rectal discomfort thresholds after sigmoid stimulation is seen in IBS regardless of specific symptoms, baseline and postsigmoid stimulation thresholds are lower in IBS patients with constipation-related symptoms.