Fecal incontinence
Fecal incontinence (FI), also known as anal incontinence, or in some forms encopresis, is a lack of control over defecation, leading to involuntary loss of bowel contents—including flatus (gas), liquid stool elements and mucus, or solid feces. FI is a sign or a symptom, not a diagnosis. Incontinence can result from different causes and might occur with either constipation or diarrhea. Continence is maintained by several interrelated factors, including the anal sampling mechanism, and usually there is more than one deficiency of these mechanisms for incontinence to develop. The most common causes are thought to be immediate or delayed damage from childbirth, complications from prior anorectal surgery (especially involving the anal sphincters or hemorrhoidal vascular cushions), altered bowel habits (e.g., caused by irritable bowel syndrome, Crohn's disease, ulcerative colitis, food intolerance, or constipation with overflow incontinence), and receptive anal sex. An estimated 2.2% of community dwelling adults are affected.
Neurogenic bowel dysfunction
The gastrointestinal tract has a complex control that relies on coordinated interaction between muscular contractions and neuronal impulses. Faecal incontinence or constipation occurs when there is a problem with the normal bowel functioning; this could be for a variety of reasons. The normal defecation pathway involves contractions of the colon in order to help mix the contents, absorb water and propel the contents along the intestine. This results in the faeces moving from the colon to the rectum. The presence of stool in the rectum causes a reflexive relaxation of the internal anal sphincter, so the contents of the rectum can move in to the anal canal. This causes the conscious feeling of the need to defecate. At a suitable time our brain can send signals causing the external anal sphincter and puborectalis muscles to relax as these are under voluntary control and this allows defecation to take place.