These are factors which all must be excluded for a diagnosis of functional FI, and are abnormal innervation caused by lesion(s) within the brain (e.g., dementia), spinal cord (at or below T12), or sacral nerve roots, or mixed lesions (e.g., multiple sclerosis), or as part of a generalized peripheral or autonomic neuropathy (e.g., due to diabetes), anal sphincter abnormalities associated with a multisystem disease (e.g., scleroderma), and structural or neurogenic abnormalities that are the major cause. Definition
There is no globally accepted definition, but fecal incontinence is generally defined as the recurrent inability to voluntarily control the passage of bowel contents through the anal canal and expel it at a socially acceptable location and time, occurring in individuals over the age of four. "Social continence" has been given various precise definitions for the purposes of research; however, generally it refers to symptoms being controlled to an extent that is acceptable to the individual in question, with no significant effect on their life. There is no consensus about the best way to classify FI, and several methods are used. Symptoms can be directly or indirectly related to the loss of bowel control. The direct (primary) symptom is a lack of control over bowel contents which tends to worsen without treatment. Indirect (secondary) symptoms, which are the result of leakage, include pruritus ani (an intense itching sensation from the anus), perianal dermatitis (irritation and inflammation of the skin around the anus), and urinary tract infections. Due to embarrassment, people may only mention secondary symptoms rather than acknowledge incontinence.
They cover a spectrum of increasing symptom severity (staining, soilage, seepage and accidents). Rarely, minor FI in adults may be described as encopresis. Fecal leakage is a related topic to rectal discharge, but this term does not necessarily imply any degree of incontinence. Discharge generally refers to conditions where there is pus or increased mucus production, or anatomical lesions that prevent the anal canal from closing fully, whereas fecal leakage generally concerns disorders of IAS function and functional evacuation disorders which cause a solid fecal mass to be retained in the rectum. Solid stool incontinence may be called complete (or major) incontinence, and anything less as partial (or minor) incontinence (i.e. incontinence of flatus (gas), liquid stool and/or mucus).In children over the age of four who have been toilet trained, a similar condition is generally termed encopresis (or soiling), which refers to the voluntary or involuntary loss of (usually soft or semi-liquid) stool. The term pseudoincontinence is used when there is FI in children who have anatomical defects (e.g. enlarged sigmoid colon or anal stenosis). Encopresis is a term that is usually applied when there are no such anatomical defects present. The ICD-10 classifies nonorganic encopresis under "behavioural and emotional disorders with onset usually occurring in childhood and adolescence" and organic causes of encopresis along with FI.