Manometric study of the voluntary inhibition action in normal volunteers.

Abstract

A voluntary inhibition action whereby a voluntary squeeze of the external sphincter causes reflex relaxation of the rectum has been previously proposed but not proven. Such a reflex would enable the subject to defer defecation to a socially acceptable time. The purpose of this study was to determine whether or not such a reflex exists. We measured rectal compliance with and without a voluntary squeeze using a specially designed balloon catheter in nine subjects. When corrected for increased intra-abdominal pressure caused by inadvertent Valsalva's maneuver during voluntary squeezing, there was a significant increase in rectal compliance during voluntary contraction of the external sphincter (P < 0.01). This lends support to the proposed existence of the voluntary inhibition action.