Abdominal symptoms and anorectal function in outpatients with the irritable bowel syndrome (IBS)

Abstract: Two samples of outpatients with the irritable bowel syndrome and 12 healthy controls were studied regarding abdominal symptoms and pre- and postprandial anorectal function. Symptoms were assessed using diary cards and anorectal function by manovolumetfY. Our aim was to study the temporal relationship between pain and eating or defecation, what patients mean by constipation and diarrhoea, symptom variation, the relation between symptoms and anorectal function, to identify symptom subgroups and to compare patients with healthy controls regarding symptoms and anorectal function.Sixty-three patients (Sample I) recorded their symptoms daily over a period of six weeks. At fortnightly follow-up visits they were asked to define their bowel habits as constipation, diarrhoea, normal or any combination of these the preceding fortnight. These statements were compared with the diary cards. According to the diary cards about 50% of each patient's pain episodes became worse after eating and about 10% were relieved by defecation. Constipation was defined as hard stools and diarrhoea as loose stools and urgency. Stool frequency was similar. Pain decreased slightly but other symptoms remained unchanged. Fifty-two patients (Sample II) and 12 healthy controls kept daily records of their symptoms over a period of one week. At the end of this week anorectal function was investigated before and after a standardised fatty meal.Cluster analysis of the diary cards detected similar subgroups in both samples. Two pain/bloating subgroups, one characterised by a considerable and the other by a low burden of pain and bloating. Three bowel habit subgroups, one characterised by hard stools, variable stool consistency and frequent straining and feeling of incomplete evacuation, the second by loose and urgent stools and the third by normal consistency stools and the least disturbed stool passage. There was no association between the degree of bloating and the type of bowel habit. Stool frequency was within the normal range in the subgroups of both samples.Thiny-seven of the 63 patients from Sample I repeated symptom recording over a period of two weeks seven years later. During the seven-year period and at follow up the majority of patients were symptomatic. According to the daily records pain and straining decreased while normal stools increased between study periods. Abdominal symptoms remained otherwise unchanged. The symptom subgroups (clusters) were similarly distinguished from each other in both study periods.Irrespective of subgroup placement the patients from Sample II recorded more pain, bloating and stools with straining and feeling of incomplete evacuation than the controls. About 50% of the patients had a lower baseline (preprandial) threshold for maximal tolerable distension than the controls. This rectal hypersensitivity was most prevalent in the bowel habit subgroup characterised by hard stools, variable stool consistency, straining and feeling of incomplete evacuation. Otherwise no relationship between abdominal symptoms and anorectal function was found. The threshold for maximal tolerable distension showed a significant and similar postprandial decrease in the patients and controls. Other manovolumetric variables remained unchanged.These studies show that pain is temporally related to eating but not to defecation. Patients define constipation and diarrhoea on the basis of stool consistency, not frequency, which is within the normal range in the majority of patients. Patients can be divided into subgroups and the symptoms remain fairly unchanged over time. Compared with controls the patients are distinguished by pain, bloating and stools with straining and feeling of incomplete evacuation. Baseline rectal hypersensitivity is associated with constipation-like bowel habits. Postprandial decrease in maximal tolerable distension is a normal phenomenon and seem to play no role in the genesis of symptoms.

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