Anal and rectal motility responses to distension of the urinary bladder in man.

Recto-anal motility response to bladder distension was studied under general anaesthesia in 12 patients undergoing intestinal resection for Crohn's disease of the small intestine or colonic cancer. The effect of epidural anaesthesia on anal tone and on the motility response to bladder distension was studied in six of these patients. An anal pressure increase on bladder distension was observed in all individuals. No motility response was noted in the rectum. The anal pressure response to bladder distension was abolished by epidural anaesthesia. It was concluded that anal pressure in man under general anaesthesia was tonically influenced by the thoracolumbar sympathetic outflow. An excitatory vesico-anal reflex was demonstrated. It appears as this reflex is mediated via the spinal cord.