Other causes of incomplete evacuation include non-emptying defects like a rectocele. Straining to defecate pushes stool into the rectocele, which acts like a diverticulum and causes stool sequestration. Once the voluntary attempt to defecate, albeit dysfunctional, is finished, the voluntary muscles relax, and residual rectal contents are then able to descend into the anal canal and cause leaking. : 37

Central nervous system
Continence requires conscious and subconscious networking of information from and to the anorectum. Defects/brain damage may affect the central nervous system focally (e.g. stroke, tumor, spinal cord lesions, trauma, multiple sclerosis) or diffusely (e.g. dementia, multiple sclerosis, infection, Parkinsons disease or drug-induced). FI (and urinary incontinence) may also occur during epileptic seizures. Dural ectasia is an example of a spinal cord lesion that may affect continence. Diarrhea
Liquid stool is more difficult to control than formed, solid stool. Hence, FI can be exacerbated by diarrhea. Some consider diarrhea to be the most common aggravating factor. Where diarrhea is caused by temporary problems such as mild infections or food reactions, incontinence tends to be short lived. Chronic conditions, such as irritable bowel syndrome or Crohns disease, can cause severe diarrhea lasting for weeks or months. Diseases, drugs, and indigestible dietary fats that interfere with the intestineal absorption may cause steatorrhea (oily rectal discharge & fatty diarrhea) and degrees of FI. Respective examples include cystic fibrosis, orlistat, and olestra. Postcholecystectomy diarrhea is diarrhea that occurs following gall bladder removal, due to excess bile acid. Orlistat is an anti-obesity (weight loss) drug that blocks the absorption of fats.
Any major underlying cause will produce additional signs and symptoms, such as protrusion of mucosa in external rectal prolapse. Symptoms of fecal leakage (FL) are similar, and may occur after defecation. There may be loss of small amounts of brown fluid and staining of the underwear. Types
FI can be divided into those people who experience a defecation urge before leakage (urge incontinence), and those who experience no sensation before leakage (passive incontinence or soiling). Urge incontinence is characterized by a sudden need to defecate, with little time to reach a toilet. Urge and passive FI may be associated with weakness of the external anal sphincter (EAS) and internal anal sphincter (IAS) respectively. Urgency may also be associated with reduced rectal volume, reduced ability of the rectal walls to distend and accommodate stool, and increased rectal sensitivity.There is a continuous spectrum of different clinical presentations from incontinence of flatus (gas), through incontinence of mucus or liquid stool, to solids. The term anal incontinence often is used to describe flatus incontinence, however it is also used as a synonym for FI generally. It may occur together with incontinence of liquids or solids, or it may present in isolation. Flatus incontinence may be the first sign of FI. Once continence to flatus is lost, it is rarely restored. Anal incontinence may be equally disabling as the other types. Fecal leakage, fecal soiling and fecal seepage are minor degrees of FI, and describe incontinence of liquid stool, mucus, or very small amounts of solid stool.