Rectoanal inhibition and incontinence in patients with rectal prolapse.

Thirty-five patients with complete rectal prolapse, 32 with neurogenic faecal incontinence and 33 controls underwent ambulatory recording using a computerized anal electromyographic and anorectal manometry system. Median resting anal pressures were 34 cmH2O in patients with prolapse, 51 cmH2O in those with neurogenic faecal incontinence and 94 cmH2O in controls. Median basal rectal pressures were 18, 21 and 21 cmH2O respectively. High-pressure rectal waves of median amplitude 71 cmH2O lasting 30-150 s and associated with inhibition of the electromyographic activity of the internal and sphincter and a fall in anal pressures were seen in all patients with prolapse but not in controls or those with neurogenic incontinence. These waves were abolished following successful resection rectopexy. Recovery of continence occurs by abolition of high-pressure rectal waves, which produce maximal inhibition of sphincter activity before operation.