Continence is far more than a sphincter mechanism; it is a complex physiological function involving the sigmoid colon, the rectum and its compliance, as well as the anus, the sphincters and pelvic floor musculature, the integrity of the afferent and efferent nervous autonomic and somatic pathways with their connections to the central nervous system and, finally, the characteristics of the faeces. A perfectly functioning dynamic neo-anal sphincter could restore just one of these factors after irremediable damage or eradication by surgery.
The major concern for surgeons facing this problem has always been control of the passage of stools (faecal continence), without worrying about the other side of the same coin: the ability to properly expel faeces (defecation).
A perineal colostomy with a dynamic neo-anal sphincter using the gracilis muscle has been demonstrated to be a feasible option for selected groups of patients who are strongly motivated to dispense with abdominal colostomy, but these patients should be fully informed and aware that, apart from the possible complications, a perineal colostomy is not a new normal anus and total anorectal reconstruction cannot reproduce a fully normal anorectal function. Not only may continence be incomplete, but rectal sensation is usually lost and defecation may also be troublesome and require daily enemas.
With this in mind one could argue whether these patients are "continent" or "constipated". In fact they could falsely be considered continent because they cannot defecate except by means of daily enemas rather than because they are able to prevent the passage of faeces and postpone defecation until the right time and place. However, although they are often more content than continent, patients with total anorectal reconstruction very rarely wish to return to an abdominal colostomy even if the per-ineal colostomy function is far from perfect.
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