<unk>  is a sign or a symptom, not a diagnosis, and represents an extensive list of causes. Usually, it is the result of a complex interplay of several coexisting factors, many of which may be simple to correct. Up to 80% of people may have more than one abnormality that is contributing. Deficits of individual functional components of the continence mechanism can be partially compensated for a certain period of time, until the compensating components themselves fail. For example, obstetric injury may precede onset by decades, but postmenopausal changes in the tissue strength reduce in turn the competence of the compensatory mechanisms. The most common factors in the development are thought to be obstetric injury and after effects of anorectal surgery, especially those involving the anal sphincters and hemorrhoidal vascular cushions. The majority of incontinent persons over the age of 18 fall into one of several groups: those with structural anorectal abnormalities (sphincter trauma, sphincter degeneration, perianal<unk> stula, rectal prolapse), neurological disorders (multiple sclerosis, spinal cord injury, spina bifida, stroke, etc.), constipation/fecal loading (presence of a large amount of feces in the rectum with stool of any consistency), cognitive and/or behavioral dysfunction (dementia, learning disabilities), diarrhea, inflammatory bowel diseases (e.g. ulcerative colitis, Crohn's disease), irritable bowel syndrome, disability related (people who are frail, acutely unwell, or have chronic/acute disabilities), and those cases which are idiopathic (of unknown cause). Diabetes mellitus is also known to be a cause, but the mechanism of this relationship is not well understood. Congenital Anorectal anomalies and spinal cord defects may be a cause in children. These are usually picked up and operated upon during early life, but continence is often imperfect thereafter. Anal canal The functioning of the anal canal can be damaged, traumatically or atraumatically. The resting tone of the anal canal is not the only factor which is important; both the length of the high pressure zone and its radial translation of force are required for continence. This means that even with normal anal canal pressure,<unk>  defects such as the keyhole deformity can be the cause of substantial symptoms. External anal sphincter (EAS) dysfunction is associated with impaired voluntary control, whereas internal anal sphincter (IAS) dysfunction is associated with impaired<unk> ne tuning of<unk>  control. Lesions which mechanically interfere with, or prevent the complete closure of the anal canal can cause a liquid stool or mucous rectal discharge. Such lesions include piles (inflamed hemorrhoids), anal<unk> ssures, anal cancer or<unk> stulae. Obstetric injury may tear the anal sphincters, and some of these injuries may be occult (undetected). The risk of injury is greatest when labor has been especially difficult or prolonged, when forceps are used, with higher birth weights or when an midline episiotomy is performed. Only when there is post operative investigation of<unk>  such as endoanal ultrasound is the injury discovered.<unk>  is a much under-reported complication of surgery. The IAS is easily damaged with an anal retractor (especially the Park's anal retractor), leading to reduced resting pressure postoperatively. Since the hemorrhoidal vascular cushions contribute 15% of the resting anal tone, surgeries involving these structures may affect continence status. Partial internal sphincterotomy,<unk> stulotomy, anal stretch (Lord's operation), hemorrhoidectomy or transanal advancement flaps may all lead to<unk>  post operatively, with soiling being far more common than solid<unk> . The "keyhole deformity" refers to scarring within the anal canal and is another cause of mucus leakage and minor<unk> . This defect is also described as a groove in the anal canal wall, and may occur after posterior midline<unk> ssurectomy or<unk> stulotomy, or with lateral IAS defects. Rare causes of traumatic injury to the anal sphincters include military or traffic accidents complicated by pelvic fractures, spine injuries or perineal lacerations, insertion of foreign bodies in the rectum, and sexual abuse. Nontraumatic conditions causing anal sphincter weakness include scleroderma, damage to the pudendal nerves and IAS degeneration of unknown cause. Radiation induced<unk>  may involve the anal canal as well as the rectum, when proctitis, anal<unk> stula formation and diminished function of internal and external sphincter occur. Irradiation may occur during radiotherapy, e.g. for prostate cancer. Pelvic floor Many people with<unk>  have a generalized weakness of the pelvic floor, especially puborectalis. A weakened puborectalis leads to widening of the anorectal angle, and impaired barrier to stool in the rectum entering the anal canal, and this is associated with<unk>  to solids. Abnormal descent of the pelvic floor can also be a sign of pelvic floor weakness. Abnormal descent manifests as descending perineum syndrome (>4 cm perineal descent). This syndrome initially gives constipation, and later<unk> . The pelvic floor is innervated by the pudendal nerve and the S3 and S4 branches of the pelvic plexus. With recurrent straining, e.g. during difficult labour or long term constipation, then stretch injury can damage the nerves supplying levator ani. The pudendal nerve is especially vulnerable to irreversible damage, (stretch induced pudendal neuropathy) which can occur with a 12% stretch. If the pelvic floor muscles lose their innervation, they cease to contract and their muscle<unk> bres are in time replaced by<unk> brous tissue, which is associated with pelvic floor weakness and<unk> . Increased pudendal nerve terminal motor latency may indicate pelvic floor weakness. The various types of pelvic organ prolapse (e.g. external rectal prolapse, mucosal prolapse and internal rectal intussusception & solitary rectal ulcer syndrome) may also cause coexisting obstructed defecation. Rectum The rectum needs to be of a sufficient volume to store stool until defecation. The rectal walls need to be "compliant" i.e. able to distend to an extent to accommodate stool. Rectal sensation is required to detect the presence, nature and amount of rectal contents. The rectum must also be able to evacuate its contents fully. There must also be efficient co-ordination of rectal sensation and relaxation of the anal canal. If the sensory nerves are damaged, detection of stool in the rectum is dulled or absent, and the person will not feel the need to defecate until too late. Rectal hyposensitivity may manifest as constipation,<unk> , or both. Rectal hyposensitivity was reported to be present in 10% of people with<unk> . Pudendal neuropathy is one cause of rectal hyposensitivity, and may lead to<unk>  loading/impaction, megarectum and overflow<unk> . Normal evacuation of rectal contents is 90-100%. If there is incomplete evacuation during defecation, residual stool will be left in the rectum and threaten continence once defecation is<unk> nished. This is a feature of people with soiling secondary to obstructed defecation. Obstructed defecation is often due to anismus (paradoxical contraction or relaxation failure of the puborectalis). Whilst anismus is largely a functional disorder, organic pathologic lesions may mechanically interfere with rectal evacuation. 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<unk> nished, the voluntary muscles relax, and residual rectal contents are then able to descend into the anal canal and cause leaking. + Drugs that may exacerbate<unk>  and diarrhea Drug/mechanism of action Common examples Drugs altering sphincter tone Nitrates, calcium channel antagonists, beta-adrenoceptor antagonists (beta-blockers), sildenafil, selective serotonin reuptake inhibitors Broad-spectrum antibiotics Cephalosporins, penicillins, macrolides Topical drugs applied to anus (reducing pressure) Glyceryl trinitrate ointment, diltiazem gel, bethanechol cream, botulinum toxin A injection Drugs causing profuse diarrhea Laxatives, metformin, orlistat, selective serotonin reuptake inhibitors, magnesium-containing antacids, digoxin Constipating drugs Loperamide, opioids, tricyclic antidepressants, aluminium-containing antacids, codeine Tranquilisers/hypnotics (reducing alertness) Benzodiazepines, tricyclic antidepressants, selective serotonin reuptake inhibitors, anti-psychotics 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<unk> ly (e.g. stroke, tumor, spinal cord lesions, trauma, multiple sclerosis) or diffusely (e.g. dementia, multiple sclerosis, infection, Parkinson's disease or drug-induced).<unk>  (and urinary<unk>  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,<unk>  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,<unk>  tends to be short lived. Chronic conditions, such as irritable bowel syndrome or Crohn's 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<unk> . Respective examples include cystic<unk> brosis, 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. This may give side effects of<unk> , diarrhea and steatorrhea. Overflow<unk>  This may occur when there is a large mass of feces in the rectum<unk>  loading), which may become hardened<unk>  impaction). Liquid stool elements are able to pass around the obstruction, leading to<unk> . Megarectum (enlarged rectal volume) and
Fecal incontinence
Open defecation
Coital incontinence
Urinary incontinence
Rectal pain
Constipation
Steatorrhea
Dysuria