Faecal Incontinence

The causes of faecal incontinence may vary and usually affect the continence organ itself. Here the term continence organ refers to the unified functioning of several anatomical structures: the rectum, which serves as a reservoir for the faecal matter, and ends with the anal sphincter, which is also a part of the pelvic floor. The sphincter consists of an involuntarily functioning internal section and a second external voluntarily controllable section. The anal canal is lined with a haemorrhoidal cushion, which is a cylindrical erectile tissue that also seals gas within the continence organ. A functioning nervous system is also important for continence.

Faecal incontinence may result if one or more sections of the continence organ become diseased or damaged. The most common cause of faecal incontinence in women is birth trauma. The anal sphincter is injured as the baby's head passes through the birth canal, causing subsequent sphincter weakness.
In other cases, a prolapse of the anal canal or the rectum results in the incomplete closure of the sphincter muscle. One reason for this may be the reduced functional ability of the pelvic floor to support the continence organ. This may again be a result of childbirth or surgery, but also of being overweight.

Haemorrhoids, which afflict many people, are often a cause of faecal incontinence, but it may also be caused by fissures (painful cracks in the anal mucosa), or fistulae, such as those occurring in Crohn's disease – an inflammatory bowel disease. Surgery or childbirth may also damage the nerves of the continence organ. Diseases of the central nervous system, such as multiple sclerosis or nerve damage associated with vertebral disk herniation, may be further causes of damage.