Motor and sensory function of the rectum in different subtypes of constipation

Background: It is not known whether evaluation of motor and sensory functio n of the rectum using a barostat may help to distinguish subtypes of consti pation. Methods: Motor and sensory function of the rectum have been evaluat ed using a barostat in 14 patients with slow transit constipation (STC), 12 patients with constipation-predominant irritable bowel syndrome (IBS) and 18 healthy controls. First minimal distending pressure was determined, afte r which spontaneous adaptive relaxation of the rectum was monitored. Then a step-wise isobaric distension procedure was performed, during which sympto m perception was determined. The distension was followed by a 90-min barost at procedure: for 30 min in the basal state followed by ingestion of a semi -liquid meal (postprandial state). Results: Minimal distending pressure was not different between both patient groups and controls, neither was compli ance different between constipated patients and controls. The degree of spo ntaneous adaptive relaxation was in the same range in all groups. During di stensions with high pressures, the perception of urge was significantly red uced in STC patients compared to IBS and controls, while the perception of pain was significantly increased in IBS versus STC and controls. Postprandi ally, a small decrease of rectal volume was only observed in the control gr oup, but not in the patients. Conclusions: Rectal motor characteristics are not different between patients with constipation-predominant IBS, patients with STC and healthy controls while during isobaric distensions, sensation s of urge were reduced in STC and sensations of pain were increased in IBS. Rectal visceroperception testing may help distinguish groups of patients w ith different subtypes of constipation.