IRRITABLE-BOWEL-SYNDROME - DIFFERENCES BETWEEN PATIENTS WHO SHOW RECTAL SENSITIVITY AND THOSE WHO DO NOT

Objective: To investigate whether measurements of rectal sensitivity may be used to segregate patients with irritable bowel syndrome into different treatment categories, intermittent phasic distension of the rectum was carried out in 55 patients with irritable bowel syndrome and 20 matched normal volunteers. Threshold volumes for sensations were compared with anorectal motor responses and symptomatic presentation. Results: Of the patients with irritable bowel syndrome, 58% had an abnormally low threshold for desire to defecate. This group also had abnormally low thresholds for sensations of urgency and discomfort, abnormally low rectal compliances (P<0.05), and abnormally low threshold volumes for the induction of repetitive rectal contractions and internal anal sphincter relaxation. Values in patients who had a non-sensitive rectum were normal. The incidence of most symptoms were similar in both irritable bowel syndrome groups though a frequent desire to defecate was more common in the sensitive group (P<0.01). Anxiety was also more common in the sensitive compared with the non-sensitive group (P<0.05). Although most sensitive patients had diarrhoea, one-third of patients with constipation were sensitive and unlike other constipated patients, they had a frequent desire to defecate. Conclusion: These results suggest that tests of rectal sensitivity may segregate patients with irritable bowel syndrome into pathophysiologically distinct subgroups.