SUBTYPES OF CONSTIPATION PREDOMINANT IRRITABLE-BOWEL-SYNDROME BASED ON RECTAL PERCEPTION

Background - Patients who complain of constipation can be divided into those who have lost the natural call to stool, but develop abdominal discomfort after several days without a bowel movement (no urge); and those who experience a constant sensation of incomplete evacuation (ur ge). Aims - To determine whether the two groups differ in symptoms, co lonic transit, and perceptual responses to controlled rectal distensio n. Methods - Forty four patients with constipation were evaluated with a bowel symptom questionnaire, colonic transit (radiopaque markers), and rectal balloon distension. Stool (S) and discomfort (D) thresholds to slow ramp (40 ml/min) and rapid phasic distension (870 ml/min) wer e determined with an electronic distension device. Fifteen healthy con trols were also studied. Results - All patients had Rome positive irri table bowel syndrome (IBS); 17 were no urge and 27 urge. Mean D thresh old to phasic rectal distensions was 28 (3) mm Hg in no urge, 27 (3) m m Hg in urge (NS), but higher in the control group (46 (2) mm Hg; p < 0.01). Sixty seven per cent of no urge and 69% of urge were hypersensi tive for D. Slow ramp distension thresholds were higher in no urge (S: 26 (3); D: 45 (4) mm Hg) compared with urge (S: 16 (2); D: 31 (3) mm Hg; p < 0.01), or with controls (S: 15 (1); D: 30 (3); p < 0.01). Conc lusions - Hyposensitivity to slow rectal distension is found in patien ts with IBS who complain of constipation and have lost the call to sto ol even though their sensitivity to phasic distension is increased.