Novel insights into physiological mechanisms underlying fecal continence

Abstract

The machinery maintaining fecal continence prevents involuntary loss of stool and is based on synchronized interplay of multiple voluntary and involuntary mechanisms, dependent on cooperation between motor responses of the musculature of the colon, pelvic floor and anorectum, and on sensory and motor neural pathways. Knowledge of the physiology of fecal continence is key towards understanding the pathophysiology of fecal incontinence. The idea that involuntary contraction of the internal anal sphincter is the primary mechanism of continence and that external anal sphincter supports continence only by voluntary contraction is outdated. Other mechanisms have come to the forefront and they have significantelly changed viewpoints on the mechanisms of continence and incontinence. And so for instance, involuntary contractions of the external anal sphincter, the puborectal muscle and the sphincter of O'Beirne have been proven to play a role in fecal continence. Also, retrograde propagating cyclic motor patterns in the sigmoid and rectum promote retrograde transit to prevent continuous flow of content into the anal canal. With this review we aim to give an overview of primary and secondary mechanisms controlling fecal continence and evaluate the strenght of evidence.

A Predictive Model to Identify the Effects of Transcutaneous Sacral Nerve Stimulation With Pelvic Floor Exercises in Fecal Incontinence After Surgery for Anorectal Malformation

“…FI after CARM surgery is usually due to poor muscular and sensory development in the anal sphincter and pelvic floor, which can impair stool continence mechanisms determined by 3 different muscles: IAS, EAS, and PRM (28). PRM is the most critical structure in stool continence because it maintains the anorectal angle (29–31). The roles of PRM in CARM have never been emphasized, although they have been put forward in a few studies (11).…”