Bladder smooth muscle dysfunction in patients with irritable bowel syndrome.

Urodynamic studies were carried out on 30 patients with irritable bowel syndrome and 30 matched controls. Fifty per cent of the irritable bowel patients compared with only 13% of the control group had evidence of bladder dysfunction (p = 0.006). In the irritable bowel group detrusor instability was observed in 10 patients compared with only one control subject (p = 0.008). A steep cystometrogram occurred in five irritable bowel patients and three controls (NS). Detrusor instability was most common in patients with a bowel habit characterised by alternating constipation and diarrhoea. This is the first study to provide objective evidence that patients with irritable bowel syndrome may have a disorder of smooth muscle or its innervation that is not confined to the gastrointestinal system.