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Faecal incontinence in Adults

Define faecal incontinence (FI)?
Faecal incontinence (FI) is the involuntary loss of solid or liquid stool. It is a sign or symptom, not a diagnosis. Current data show that 1-10% of adults may be affected. Its prevalence is disproportionally higher in women.
What are the subtypes of FI?
Clinically there are three subtypes

  • Passive incontinence—the involuntary discharge of stool or gas without awareness. This suggests a loss of perception and/or impaired rectoanal reflexes either with or without sphincter dysfunction.
  • Urge incontinence—the discharge of faecal matter in spite of active attempts to retain bowel contents. There is a predominant disruption of the sphincter function or the rectal capacity to retain stool.
  • Faecal seepage—the leakage of stool following otherwise normal evacuation. This condition is mostly due to incomplete evacuation of stool and/or impaired rectal sensation. The sphincter function and pudendal nerve function are mostly intact.

There is usually an overlap between these three groups.
Discuss the functional anatomy and physiology of anorectum?
The anus (2–4 cm long) at rest forms an angle with the axis of the rectum. At rest, the anorectal angle is approximately 90 degrees, with voluntary squeeze it becomes more acute, approximately 70 degrees, and during defecation it becomes more obtuse, about 110–130 degrees.
The anal sphincter consists of the internal anal sphincter, which is circular smooth muscle layer of the rectum, and the external anal sphincter which is an expansion of the striated levator ani muscles.  The anus is normally closed by the tonic activity of the internal anal sphincter and this barrier is reinforced by the external anal sphincter during voluntary squeeze. These mechanical barriers are augmented by the puborectalis muscle, which forms a flap-like valve that creates a forward pull and reinforces the anorectal angle to prevent incontinence.
The principal nerve of the anorectum is the pudendal nerve (S2-4). It innervates the external anal sphincter, the anal mucosa, and the anorectal wall. This is a mixed nerve and sub serves both sensory and motor function. Its course through the pelvic floor makes it vulnerable to stretch injury, particularly during vaginal delivery. The sacral nerves (S2-4) are intimately involved with the sensory, motor and autonomic function of the anorectum and in maintaining continence.
Discuss the population at risk of FI?
High-risk groups are:

  • frail older people
  • people with loose stools or diarrhoea from any cause
  • women following childbirth (esp. following third & fourth degree obstetric injury)
  • people with neurological or spinal disease/injury (for example, spina bifida, stroke, multiple sclerosis, spinal cord injury)
  • people with severe cognitive impairment
  • people with urinary incontinence
  • people with pelvic organ prolapse and/or rectal prolapsed
  • people who have had colonic resection or anal surgery
  • people who have undergone pelvic radiotherapy
  • people with perianal soreness, itching or pain
  • people with learning disabilities.

Discuss the initial assessment of patients with FI?

  1. Relevant medical history- any change in bowel habit, details of FI- how often, how much, consistency, urge, post defecation soiling etc. Past medical history of any neurological illness, obstetric history, perianal trauma or surgery, h/o urinary incontinence, rectal prolapsed.
  2. Medication review- many drugs aggravate FI –

Drugs altering sphincter tone- Nitrates, Calcium channel antagonists, beta-blockers, Sildenafil, Selective serotonin reuptake inhibitors
Broad-spectrum antibiotics (multiple mechanisms) – Cephalosporins, Penicillins, Erythromycin
Topical drugs applied to anus (reducing pressure) – Glyceryl trinitrate ointment,
Diltiazem gel, Bethanechol cream, Botulinum toxin A injection
Drugs causing profuse loose stools- Laxatives, Metformin, Orlistat, Selective serotonin reuptake inhibitors, Magnesium-containing antacids, Digoxin
Constipating drugs- Loperamide, Opioids, Tricyclic antidepressants, Aluminium-containing antacids, Codeine
Tranquillisers or hypnotics (reducing alertness) – Benzodiazepines, Tricyclic antidepressants
Selective serotonin reuptake inhibitors, Anti-psychotics

3.   Diet and fluid history- Certain food/drinks may exacerbate FI in those presenting FI and loose stools or rectal loading of loose stools. Examples- fibre, beans, pulses, cabbage, artificial

sweeteners’, alcohol, caffeine, lactose etc. Rhubarb, figs, prunes and plums best avoided as contain natural laxative compounds
4.   Impact of symptoms on QoL/life style
5.   Physical examination

  • General examination (as indicated)
  • Cognitive and behavioural assessment (if indicated)
  • Assess patient’s ability to use toilet, including: Access and Mobility
  • Anorectal examination:
    • Visual inspection of anus
    • Assessment of perineal descent (assessed by asking the patient to attempt defecation)
    • Digital rectal examination for anal tone, ability to squeeze anal sphincter voluntarily (It is not accurate enough for diagnosing sphincter dysfunction)
    • Assessment of faecal loading

The initial assessment may reveal a few conditions which should be addressed with condition-specific interventions before progressing to initial management of faecal incontinence:

  • faecal loading
  • treatable causes of diarrhoea (for example, infective, inflammatory bowel disease and irritable bowel syndrome)
  • warning signs for lower gastrointestinal cancer
  • rectal prolapse or third-degree haemorrhoids
  • acute anal sphincter injury including obstetric and other trauma
  • acute disc prolapse/cauda equina syndrome.

Discuss the initial management of FI?

Initial management will involve attempting to reverse or remedy factors identified as contributing to FI in the baseline assessment.

  1. Address the individual’s bowel habit, aiming for ideal stool consistency and satisfactory bowel emptying at a predictable time. This can be done by:
    • encouraging bowel emptying after a meal (to utilise the gastrocolic response)
    • ensuring toilet facilities are private and comfortable and can be used in safety with sufficient time allowed
    • encouraging people to adopt a sitting or squatting position where possible while emptying the bowel
    • teaching people techniques to facilitate bowel evacuation and stressing the importance of avoiding straining
  2. Diet and fluid intake-
    • Encourage people with hard stools and/or clinical dehydration to aim for at least 1.5 litres’ intake of fluid per day.
    • Avoiding food which may exacerbate FI (as above)
  3. Medications
    • Review medications as above and consider alternatives to drugs that might be contributing to FI
    • Antidiarrhoeal medication (loperamide, codeine phosphate or co-phenotrope) should be offered to people with faecal incontinence associated with loose stools once other causes have been excluded.
    • Patients with faecal loading will need enemas and/or laxatives
  4. Other measures
    • Skin care- The majority of people with FI does not experience regular sore skin around the anus. However, certain patients seem to be prone to this. Keeping the skin clean and dry is important in maintaining skin integrity. Foam cleanser was better than soap and water in preventing skin deterioration in doubly incontinent elderly hospital or nursing home residents. Sudocrem improved skin condition over two weeks compared to a zinc oxide cream in incontinent elderly hospital patients.
    • People experiencing faecal incontinence often need to wear a product (absorbent product or plug) for containment. Devices such as anal plugs or faecal collectors have limited use, and are generally only acceptable to certain populations. Although anal plugs are not tolerated by all patients, they may be helpful in preventing FI in selected groups, such as patients with neurological impairment who have less anal sensation. Both the anal plug and faecal collectors may possibly be of help in palliative care; a collector in situations where a patient has acute profuse diarrhoea (for example in intensive care situations).
    • Ongoing support.

Discuss investigations for FI?

Endoscopic evaluation of the rectosigmoid region is appropriate for detecting mucosal disease or neoplasia that may contribute to FI. Several specific tests are available for defining the underlying mechanisms of FI. These tests are often complementary. The most useful tests are anorectal manometry, anal endosonography and pudendal nerve terminal motor latency

Anorectal physiology studies (functional assessment like rectal compliance, anal manometry, rectal distension sensitivity, pudendal nerve terminal motor latency (PNTML), anal EMG and electro sensitivity testing)-  Anorectal manometry with rectal sensory testing is the preferred method for defining the functional weakness of the external or internal anal sphincter and for detecting abnormal rectal sensation. The resting anal sphincter pressure predominantly represents the internal anal sphincter function and the voluntary squeeze anal pressure predominantly measures the external anal sphincter function. Patients with incontinence have been shown to have low resting and low squeeze sphincter pressures.
Rectal balloon distention with either air or water can be used for the assessment of both the sensory responses and the compliance of the rectal wall. By distending a balloon in the rectum with incremental volumes, it is possible to assess the thresholds for first perception, a first desire or an urgent desire to defecate. A higher threshold for sensory perception suggests impaired rectal sensation.
PNTML- It measures neuromuscular integrity between the terminal portion of the pudendal nerve and the anal sphincter. It can help to distinguish a weak sphincter muscle due to muscle injury from that due to nerve injury. A prolonged nerve latency time suggests pudendal neuropathy. A normal PNTML does not exclude pudendal neuropathy, because the presence of a few intact nerve fibers can give a normal result, whereas an abnormal latency time is more significant. PNTML is particularly helpful in predicting the outcome of surgery. Patients with pudendal neuropathy generally have a poor surgical outcome when compared to those without neuropathy.
However, there are no accepted standards for performing these tests and no ‘normal ranges’ agreed or validated. Digital examination is a poor predictor of manometric findings.
Anorectal manometry helps to perform biofeedback training and is also useful in assessing objective improvement following drug therapy, biofeedback therapy, or surgery.

Endoanal ultrasound- It is most widely available and least expensive test for defining structural defects of the anal sphincter. MRI is an alternative to endoanal ultrasound.

Defaecating proctogram- is useful in patients with suspected rectal prolapse but it is otherwise of limited value. It is used to assess several parameters such as the anorectal angle, pelvic floor descent, length of anal canal, presence of a rectocele, rectal prolapse, or mucosal intussusception. Approximately 150 ml of contrast material is placed into the rectum and the subject is asked to squeeze, cough, or expel the contrast.  The functional significance of identifying morphological defects has been questioned.
Undoubtedly, the aforementioned tests help to define the underlying mechanisms, but there is only limited information regarding their clinical utility and their impact on management.
Discuss specific management of FI?
People who continue to have episodes of FI after initial management (as above) should be considered for specialised management. This may involve referral to a specialist continence service, which may include:

  • pelvic floor muscle training
  • biofeedback
  • rectal irrigation.
  • Surgery

Pelvic floor muscle training- These might be self-directed, taught via verbal and/or written instructions from a health professional, or taught during a vaginal or anal digital examination. A patient specific exercise regimen should be provided based on the findings of digital assessment. The progress of people having pelvic floor muscle training should be monitored by digital reassessment.
Biofeedback- The governing principle is that an individual acquires a new behaviour through a process of trial and error. The goals of biofeedback therapy in a patient with faecal incontinence are:

  • to improve the strength of the anal sphincter muscles;
  • to improve the coordination between the abdominal, gluteal, and anal sphincter muscles during voluntary squeeze and following rectal perception;
  • to enhance the anorectal sensory perception.

At the outset, it is often difficult to predict how many biofeedback treatment sessions are required. Most patients seem to require between four to six training sessions. It is unclear which component of biofeedback therapy is most effective and which patients are suitable for this therapy. Hence, biofeedback therapy should be offered to all patients with faecal incontinence who have failed supportive measures, and especially to older patients and those with co morbid illnesses, to those with pudendal neuropathy and to those patients before reconstructive surgery.
The following modalities of biofeedback for FI are described in the literature:
Rectal sensitivity training: a rectal balloon is gradually distended with air or water and the patient is asked to report first sensation of rectal filling. Once this threshold volume is determined, repeated re-inflations of the balloon are performed, the objective being to teach the patient to perceive the distension at progressively lower volumes. The rationale is that some patients are found to have high threshold volumes and if the patient can detect stool arriving earlier, there is more possibility to either find a toilet or use an anal squeeze, or both. Conversely, the same technique has also been used in those with urgency and a hypersensitive rectum to teach the patient to tolerate progressively larger volumes.
Strength training: biofeedback techniques have been used to demonstrate anal sphincter pressures or activity to the patient, thereby enabling teaching of anal sphincter exercises and giving feedback on performance and progress. This can be achieved by using EMG skin electrodes, a manometric pressure probe, intra-anal EMG, or anal ultrasound. The patient is encouraged, by seeing or hearing the signal, to enhance squeeze strength and endurance. The digital assessment may be used to develop a patient-specific exercise regimen. There is no consensus on an optimum exercise regimen for use at home between sessions, or on the number of squeezes, the frequency of exercises or treatment duration, with different authors describing very different programmes.
Co-ordination training: some authors have described a three-balloon system for biofeedback for FI. One distension balloon is situated in the rectum; the second and third smaller pressure recording balloons are situated in the upper and lower anal canal. Rectal distension triggers the recto-anal inhibitory reflex. This momentary anal relaxation is a point of vulnerability for people with FI and incontinence can occur at this time. By distending the rectal balloon and showing the patient this consequent pressure drop, the aim is to teach the patient to counteract this by a voluntary anal squeeze, hard enough and for long enough for resting pressure to return to its baseline level.
The three methods described above are not mutually exclusive, and many protocols combine two or three elements together.
The evidence does not show biofeedback to be more effective than standard care, exercises alone, or other conservative therapies. The limited number of studies and the small number of participants in each group of the studies make it difficult to come to any definitive conclusion about its effectiveness.

Surgical management:
Surgery is only offered to those patients with structural or functional anal sphincter defect and a normal PNTML who have failed conservative measures or biofeedback therapy. There are a number of surgical options for faecal incontinence, these include:
Sphincter repair/Sphincteroplasty- the external anal sphincter can be repaired or simply tightened to try and improve control.
Neosphincter- In those patients with severe structural damage of the anal sphincter and significant incontinence, neo-sphincter construction has been attempted using two different approaches: (1) construction of a neo-sphincter from autologous skeletal muscle, often the gracilis and rarely the glutei (A nerve stimulator is inserted to make the muscle contract tonically) and (2) the use of an artificial bowel sphincter- it is a cuff made of silicone that encircles the anus and contains liquid that is transferred between a reservoir and the cuff. This either opens or closes the anal canal.
Levatorplasty – an alternative approach in patients with no definable sphincter defect is to tighten or to plicate the external anal sphincter (EAS) and pelvic floor muscles (levatorplasty). This involves bringing together the muscles of the pelvic floor above the anal canal. The objective is to lengthen the anal canal and augment an anal sphincter repair if performed at the same time.
Sacral nerve stimulation (SNS) – a recent innovation is sacral nerve stimulation. This technique involves stimulating the sacral nerves S3 or S4. Its main advantage is that a trial period of temporary stimulation (percutaneous nerve evaluation) only involves simple insertion of stimulating wires into the back is possible. If this is successful, the patient can have an implantable stimulator to modulate sacral nerve function.
Irrigation ports – irrigation can be performed through the anus or if unsuccessful, surgically constructed, lavage systems can be considered. One option is to bring the appendix onto the abdominal wall to allow catheters to be inserted into the colon (ACE or Malone operation). Liquids and laxatives can be instilled to wash out the colon. Another more complicated approach is to create a ‘T’ junction with the transverse colon to bring out a loop with a continent valve onto the abdominal wall. Percutaneous endoscopic colostomy (PEC) places an artificial irrigation tube into the colon, usually in the descending (left) colon. The patient then washes out the colon when appropriate. The major problem with PEC is that the device is foreign to the body and sepsis requiring removal is common.

Stoma - a stoma (usually a colostomy) may be considered for severe uncontrolled FI.  The selection process for a particular operation can be difficult. The initial surgical management will depend on the severity of the clinical symptoms and the anatomy of the sphincter as depicted by anal ultrasonography or MRI.

References

  1. NICE guidance 2007
  2. Rao SS. Diagnosis and Management of Fecal Incontinence. American College of Gastroenterology Practice Parameters Committee. Am J Gastroenterol. 2004 Aug; 99(8):1585-604

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