VISIBLE ABDOMINAL DISTENSION AND GAS SURFACE - DESCRIPTION OF AN AUTOMATIC METHOD OF EVALUATION AND APPLICATION TO PATIENTS WITH IRRITABLE-BOWEL-SYNDROME AND DYSPEPSIA

Objective: To estimate the gas surface in patients with irritable bowel syndrome and to correlate this parameter to Manning's criteria. Design: Prospective multicentre study. Abdominal plain X-ray, questionnaire and coloscopy were performed in all patients included. Gas surface was assessed on the film by a scan connected to a microcomputer. The observer was not aware of the clinical diagnosis. Patients: Ninety-seven patients with irritable bowel syndrome, 37 with non-ulcer dyspepsia and 94 with organic gastrointestinal disease. Main outcome measures: Gas surface according to the diagnosis and the presence of visible abdominal distension. Results. The computerized estimate was highly correlated to the paper-weight method (R = 0.996; P < 0.0001). Among patients with irritable bowel syndrome, the gas surface was 28% higher in the 61 patients with the first of Manning's criteria: 'visible abdominal distension' (4325 +/- 289 pixel2; m +/- SEM) compared with 36 patients without this symptom (3376 +/- 223 pixel2: p < 0.04). This difference persisted after adjustment (regression analysis) by sex (35% in women and 25% in men), age, weight and height. Among those with organic disease there was a difference between 38 patients with (5492 +/- 5121) and 38 patients without 'distension' (3702 +/- 307 pixel2; P < 0.003). Conclusions: It is possible to have an easy quantitative estimate of gas surface on an abdominal plain X-ray film by a scan connected to a computer. Patients with irritable bowel syndrome who show 'visible abdominal distension' have a higher gas surface than those without this Manning's criteria. These findings suggest that visceral sensitivity is not the only mechanism in these patients and that gas volume should also have a role in patients with irritable bowel syndrome.