SUMMARY BackgroundA sensation of abdominal swelling (bloating) and actual increase in girth (distension) are troublesome features of irritable bowel syndrome (IBS), which is more common in patients with constipation, especially those with delayed transit.

Abdominal distention is a clearly definable phenomenon in IBS that can reach 12 cm. However, it only occurs in half of patients reporting bloating, and the 2 only correlate in IBS-constipation. Bloating and distention may differ pathophysiologically and this appears to be reflected in the bowel habit subtype.

Background-Abdominal distension is one of the cardinal features of irritable bowel syndrome (IBS) with patients often ranking it as more intrusive than their pain or bowel dysfunction. If this symptom could be quantified accurately and reliably it would provide, for the first time, an objective way of assessing this disorder. Using the principle of inductance plethysmography we have developed a microprocessor based system capable of recording even minimal changes in girth over 24 hours and we describe its validation and establish normal ranges. Methods-Twenty four hour recordings were made in 20 healthy female volunteers (aged 23-58 years) to assess changes in abdominal girth with respect to time, posture, meals, and sleep. Normal daily activity was encouraged and meals were standardised. The feeling of abdominal distension was also assessed using a visual analogue scale. Findings-Measurement of abdominal girth using abdominal inductance plethysmography (AIP) at a static point in time showed a close relationship with that measured using a tape measure (rho=0.8910, p<0.001). Furthermore, girth was significantly greater both in the sitting and standing postures compared with lying (p<0.01). Measurement over a 24 hour period showed that girth was significantly greater at the end compared with the beginning of the day, and ingestion of a standard meal also increased its value (p<0.05). Sleep was associated with a reduction in girth (p<0.05). Conclusions-AIP promises to add an objective dimension to the assessment of IBS which could prove invaluable in clinical trials. Furthermore, it should aid research into the pathogenesis of this symptom for which no satisfactory explanation has yet emerged. (Gut 2001;48:216-220)

IBS-C patients with delayed transit show greater abdominal distension than do those with normal transit. Therefore, drugs that accelerate transit may be expected to alleviate this troublesome problem.

The symptom of bloating alone is associated with visceral hypersensitivity, suggesting that the pathogenesis of bloating and distention may not be the same. Consequently, treatment approaches may have to be different, and measuring visceral sensation could have utility in choosing the right therapeutic modality.