Fecal incontinence

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.[5]

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, focal 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 fine tuning of fecal control.[1] 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 fissures, anal cancer or fistulae. 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 FI such as endoanal ultrasound is the injury discovered.[5] FI 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.[5] Partial internal sphincterotomy, fistulotomy, anal stretch (Lord's operation), hemorrhoidectomy or transanal advancement flaps may all lead to FI post operatively, with soiling being far more common than solid FI. The "keyhole deformity" refers to scarring within the anal canal and is another cause of mucus leakage and minor incontinence. This defect is also described as a groove in the anal canal wall, and may occur after posterior midline fissurectomy or fistulotomy, 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.[5] Nontraumatic conditions causing anal sphincter weakness include scleroderma, damage to the pudendal nerves and IAS degeneration of unknown cause.[6] Radiation induced FI may involve the anal canal as well as the rectum, when proctitis, anal fistula formation and diminished function of internal and external sphincter occur.[5] Irradiation may occur during radiotherapy, e.g. for prostate cancer.

Many people with FI have a generalized weakness of the pelvic floor, especially puborectalis.[6] 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 incontinence 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).[6] This syndrome initially gives constipation, and later FI. 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.[5] If the pelvic floor muscles lose their innervation, they cease to contract and their muscle fibres are in time replaced by fibrous tissue, which is associated with pelvic floor weakness and incontinence. 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.

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.[12] Rectal storage capacity (i.e. rectal volume + rectal compliance) may be affected in the following ways. Surgery involving the rectum (e.g. lower anterior resection, often performed for colorectal cancer), radiotherapy directed at the rectum, and inflammatory bowel disease can cause scarring, which may result in the walls of the rectum becoming stiff and inelastic, reducing compliance. Reduced rectal storage capacity may lead to urge incontinence, where there is an urgent need to defecate as soon as stool enters the rectum, where normally stool would be stored until there was enough to distend the rectal walls and initiate the defecation cycle. Tumors and strictures also may impair reservoir function. Conversely, increased rectal volume (megarectum), may cause fecal loading and overflow FI. Reduced rectal sensation may be a contributory factor. 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, FI, or both. Rectal hyposensitivity was reported to be present in 10% of people with FI.[13] Pudendal neuropathy is one cause of rectal hyposensitivity, and may lead to fecal loading/impaction, megarectum and overflow FI.[14] Normal evacuation of rectal contents is 90-100%.[5] If there is incomplete evacuation during defecation, residual stool will be left in the rectum and threaten continence once defecation is finished. This is a feature of people with soiling secondary to obstructed defecation.[15] Obstructed defecation is often due to anismus (paradoxical contraction or relaxation failure of the puborectalis).[5]^:38 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 finished, the voluntary muscles relax, and residual rectal contents are then able to descend into the anal canal and cause leaking.[5]^:37

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, Parkinson's disease or drug-induced).[1][17] FI (and urinary incontinence) may also occur during epileptic seizures.[18] Dural ectasia is an example of a spinal cord lesion that may affect continence.[19]

Liquid stool is more difficult to control than formed, solid stool. Hence, FI can be exacerbated by diarrhea.[7] Some consider diarrhea to be the most common aggravating factor.[5] 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 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 FI. Respective examples include cystic fibrosis, orlistat, and olestra. Postcholecystectomy diarrhea is diarrhea that occurs following gall bladder removal, due to excess bile acid.[20] Orlistat is an anti-obesity (weight loss) drug that blocks the absorption of fats. This may give side effects of FI, diarrhea and steatorrhea.[21]

This may occur when there is a large mass of feces in the rectum (fecal loading), which may become hardened (fecal impaction). Liquid stool elements are able to pass around the obstruction, leading to incontinence. Megarectum (enlarged rectal volume) and rectal hyposensitivity are associated with overflow incontinence. Hospitalized patients and care home residents may develop FI via this mechanism,[7] possibly a result of lack of mobility, reduced alertness, constipating effect of medication and/or dehydration.

There is no globally accepted definition,[1] 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.[1][5][6][7][9] "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,[7] 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.[1] Due to embarrassment, people may only mention secondary symptoms rather than acknowledge incontinence. 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.[5]

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).[7] 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.[6]

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,[7] 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.[5] Once continence to flatus is lost, it is rarely restored.[7] Anal incontinence may be equally disabling as the other types.[26] 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. They cover a spectrum of increasing symptom severity (staining, soilage, seepage and accidents).[1] 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).[5]

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.[27] The term pseudoincontinence is used when there is FI in children who have anatomical defects (e.g. enlarged sigmoid colon or anal stenosis).[5] 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.[28] FI can also be classified according to gender, since the cause in females may be different from males, for example it may develop following radical prostatectomy in males,[29] whereas females may develop FI as an immediate or delayed consequence of damage whilst giving birth. Pelvic anatomy is also different according to gender, with a wider pelvic outlet in females.

Several severity scales exist. The Cleveland Clinic (Wexner) fecal incontinence score takes into account five parameters that are scored on a scale from zero (absent) to four (daily) frequency of incontinence to gas, liquid, solid, of need to wear pad, and of lifestyle changes.[1] The Park's incontinence score uses four categories:

1 - those continent for solid and liquid stool and also for flatus.

2 - those continent for solid and liquid stool but incontinent for flatus (with or without urgency).

3 - those continent for solid stool but incontinent for liquid stool or flatus.

4 - those incontinent to formed stool (complete incontinence).[30]

The fecal incontinence severity index is based on four types of leakage (gas, mucus, liquid stool, solid stool) and five frequencies (once to three times per month, once per week, twice per week, once per day, twice or more per day). Other severity scales include: AMS, Pescatori, Williams score, Kirwan, Miller score, Saint Mark's score and the Vaizey scale.[5]

FI may present with signs similar to rectal discharge (e.g. fistulae, proctitis or rectal prolapse), pseudoincontinence, encopresis (with no organic cause) and irritable bowel syndrome.[5]

Dietary modification may be important for successful management.[6] Both diarrhea and constipation can contribute to different cases, so dietary advice must be tailored to address the underlying cause or it may be ineffective or counter productive. In persons with disease aggravated by diarrhea or those with rectal loading by soft stools, the following suggestions may be beneficial: increase dietary fiber; reduce wholegrain cereals/bread; reduce fruit and vegetables which contain natural laxative compounds (rhubarb, figs, prunes/plums); limit beans, pulses, cabbage and sprouts; reduce spices (especially chilli); reduce artificial sweeteners (e.g. sugar free chewing gum); reduce alcohol (especially stout, beer and ale); reduce lactose if there is some degree of lactase deficiency; and reduce caffeine. Caffeine lowers the resting tone of the anal canal and also causes diarrhea. Excessive doses of vitamin C, magnesium, phosphorus and/or calcium supplements may increase FI. Reducing olestra fat substitute, which can cause diarrhea, may also help.[31]

Pharmacological management may include anti-diarrheal/constipating agents and laxatives/stool bulking agents. Stopping or substituting any previous medication that causes diarrhea may be helpful in some (see table). There is not good evidence for the use of any medications, however.[32]

In people who have undergone gallbladder removal, the bile acid sequestrant cholestyramine may help minor degrees of FI.[33] Bulking agents also absorb water, so may be helpful for those with diarrhea. A common side effect is bloating and flatulence. Topical agents to treat and prevent dermatitis may also be used, such as topical antifungals when there is evidence of perianal candidiasis or occasionally mild topical anti-inflammatory medication. Prevention of secondary lesions is carried out by perineal cleansing, moisturization, and use of a skin protectant.[34]

Evacuation aids (suppositories or enemas) e.g. glycerine or bisacodyl suppositories may be prescribed. People may have poor resting tone of the anal canal, and consequently may not be able to retain an enema, in which case transanal irrigation (retrograde anal irrigation) may be a better option, as this equipment utilizes an inflatable catheter to prevent loss of the irrigation tip and to provide a water tight seal during irrigation. A volume of lukewarm water is gently pumped into the colon via the anus. People can be taught how to perform this treatment in their own homes, but it does require special equipment. If the irrigation is efficient, stool will not reach the rectum again for up to 48 hours.[35] By regularly emptying the bowel using transanal irrigation, controlled bowel function is often re-established to a high degree in patients with bowel incontinence and/or constipation. This enables control over the time and place of evacuation and development of a consistent bowel routine.[35] However, persistent leaking of residual irrigation fluid during the day may occur and make this option unhelpful, particularly in persons with obstructed defecation syndrome who may have incomplete evacuation of any rectal contents. Consequently, the best time to carry out the irrigation is typically in the evening, allowing any residual liquid to be passed the next morning before leaving the home. Complications such as electrolyte imbalance and perforation are rare. The effect of transanal irrigation varies considerably. Some individuals experience complete control of incontinence, and other report little or no benefit.[35] It has been suggested that if appropriate, people be offered home retrograde anal irrigation.[7]

Biofeedback (the use of equipment to record or amplify and then feed back activities of the body) is a commonly used and researched treatment, but the benefits are uncertain.[36] Biofeedback therapy varies in the way it is delivered, but it is unknown if one type has benefits over another.[36]

The role of pelvic floor exercises and anal sphincter exercises in FI is poorly determined. While there may be some benefit they appear less useful than implanted sacral nerve stimulators. These exercises aim to increase the strength of the pelvic floor muscles (mainly levator ani). The anal sphincters are not technically part of the pelvic floor muscle group, but the EAS is a voluntary, striated muscle which therefore can be strengthened in a similar manner. It has not been established whether pelvic floor exercises can be distinguished from anal sphincter exercises in practice by the people doing them. This kind of exercise is more commonly used to treat urinary incontinence, for which there is a sound evidence base for effectiveness. More rarely are they used in FI. The effect of anal sphincter exercises are variously stated as an increase in the strength, speed or endurance of voluntary contraction (EAS).[36]

Electrical stimulation can also be applied to the anal sphincters and pelvic floor muscles, inducing muscle contraction without traditional exercises (similar to transcutaneous electrical nerve stimulation, TENS). The evidence supporting its use is limited, and any benefit is tentative.[37] In light of the above, intra-anal electrical stimulation (using an anal probe as electrode) appears to be more efficacious than intra-vaginal (using a vaginal probe as electrode).[37] Rarely, skin reactions may occur where the electrodes are placed, but these issues typically resolve when the stimulation is stopped. Surgically implanted sacral nerve stimulation may be more effective than exercises, and electrical stimulation and biofeedback may be more effective than exercises or electrical stimulation by themselves.[36] TENS is also sometimes used to treat FI by transcutaneous tibial nerve stimulation.[38]

In a minority of people, anal plugs may be useful for either standalone therapy or in concert with other treatments.[39] Anal plugs (sometimes termed tampons) aim to block involuntary loss of fecal material, and they vary in design and composition.[7] Polyurethane plugs were reported to perform better than those made of polyvinyl-alcohol.[39] Plugs are less likely to help those with frequent bowel movements,[5] and many find them difficult to tolerate.[39]

In women, a device that functions as an inflatable balloon in the vagina, has been approved for use in the United States.[40]

Surgery may be carried out if conservative measures alone are not sufficient to control incontinence. There are many surgical options, and their relative effectiveness is debated due to a lack of good quality evidence. The optimal treatment regime may be a both surgical and non-surgical treatments.[41] The surgical options can be considered in four categories: restoration and improvement of residual sphincter function (sphincteroplasty, sacral nerve stimulation, tibial nerve stimulation, correction of anorectal deformity), replacement / imitation of the sphincter or its function (anal encirclement, SECCA procedure, non-dynamic graciloplasty, perianal injectable bulking agents), dynamic sphincter replacement (artificial bowel sphincter, dynamic graciloplasty), antegrade continence enema (Malone procedure), and finally fecal diversion (e.g. colostomy).[1] A surgical treatment algorithm has been proposed. Isolated sphincter defects (IAS/EAS) may be initially treated with sphincteroplasty and if this fails, the person can be assessed for sacral nerve stimulation. Functional deficits of the EAS and/or IAS (i.e. where there is no structural defect, or only limited EAS structural defect, or with neurogenic incontinence) may be assessed for sacral nerve stimulation. If this fails, neosphincter with either dynamic graciloplasty or artificial anal sphincter may be indicated. Substantial muscular and/or neural defects may be treated with neosphincter initially.[9]

Some insults in Japan relate to incontinence, such as kusotare/kusottare and shikkotare which mean shit hanger/leaker/oozer and piss leaker/oozer respectively, though these have not been in common use since the 1980s.[54]